Abdominal adhesions are bands of tissue that form between abdominal tissues and organs. these vary from a consistency of wet tissue paper, which are of little significance, to a strong, fibrous band that can readily cause obstruction. Normally, in...

Abdominal migraine in children facts Abdominal migraine is believed to be a variant of migraine that is common in children but rare in adults. Abdominal migraine is characterized by pain in the center of the abdomen that m...

Abdominal migraine in children facts Abdominal migraine is believed to be a variant of migraine that is common in children but rare in adults. Abdominal migraine is characterized by pain in the center of the abdomen that m...

Gastroschisis is a rare congenital disorder in which a defect is present in the wall of the abdomen. Typically there is a small abdominal cavity with herniated abdominal organs that usually appear on the right side of the abdomen. There is no memb...

Seborrheic Keratosis is a skin disorder usually characterized by discolored lesions that appear to be "stuck on" the skin surface. Warts may appear and skin is often oily or greasy. These skin lesions are sometimes mistaken for cancerous growths a...

Cayler syndrome, also known as "asymmetric crying facies with cardiac defects," is an extremely rare disorder characterized by congenital heart defects and the underdevelopment or absence of one of the muscles that control the movements of the low...

Cayler syndrome, also known as "asymmetric crying facies with cardiac defects," is an extremely rare disorder characterized by congenital heart defects and the underdevelopment or absence of one of the muscles that control the movements of the low...

Achard-Thiers syndrome is a rare disorder that occurs primarily in postmenopausal women and is characterized by type 2 (insulin-resistant) diabetes mellitus and signs of androgen excess. The exact cause of this syndrome is unknown....

Malignant large bowel cystadenocarcinoma is quite treatable and frequently cured when it only affects the digestive system. 1. One-stage resection anastomosis, which can be subtotal colectomy or segmental colectomy, w...

What Is Tobacco Addiction? When people are addicted, they have a compulsive need to seek out and use a substance, even when they understand the harm it can cause. Tobacco products -- cigarettes, cigars, pipes, and smokeless tobacco -- can ...

What Is Tobacco Addiction? When people are addicted, they have a compulsive need to seek out and use a substance, even when they understand the harm it can cause. Tobacco products -- cigarettes, cigars, pipes, and smokeless tobacco -- can ...

Classical lissencephaly, also known as lissencephaly type I, is a brain malformation that may occur as an isolated abnormality (isolated lissencephaly sequence [ILS]) or in association with certain underlying syndromes (e.g., Miller-Dieker syndrom...

Primary aldosteronism (al-DOS-tuh-ro-niz-um) is a type of hormonal disorder that leads to high blood pressure. Your adrenal glands produce a number of essential hormones. One of these is aldosterone, which balances sodium and potassium in your blo...

Allergic granulomatosis also known as Eosinophilic granulomatosis with polyangiitis (EGPA, formerly Churg-Strauss Syndro...

Allergic granulomatosis and angiitis or Eosinophilic granulomatosis with polyangiitis is a condition that affects the sm...

What is alpha thalassemia? Alpha thalassemia is a blood disorder that reduces the production of normal hemoglobin. Hemoglobin is the protein in red blood cells that carries oxygen to cells throughout the body. What are the types of...

Alzheimer's disease is a progressive neurologic disorder that causes the brain to shrink (atrophy) and brain cells to die. Alzheimer's disease is the most common cause of dementia — a continuous decline in thinking, behavioral and social ski...

Alzheimer's disease is a progressive neurologic disorder that causes the brain to shrink (atrophy) and brain cells to die. Alzheimer's disease is the most common cause of dementia — a continuous decline in thinking, behavioral and social ski...

Amelogenesis Imperfecta is a rare genetic disorder that affects the development of tooth enamel. People with this condition have abnormal enamel formation, which can result in teeth that are discolored, pitted, or prone to rapid wear and breakage....

An aneurysm is an abnormal area of localized widening of a blood vessel. The aorta bulges at the site of an aneurysm like a weak spot on a worn tire. Aortic aneurysms are typically spindle-shaped and involve the aorta belo...

What is angina? The heart is the pump responsible for circulating blood throughout the body. Myocardium (myo=muscle + cardium=muscle) is the heart muscle that contracts to pump that blood and like any other muscle, it requires oxygen rich ...

The heart is the pump responsible for circulating blood throughout the body. Myocardium (myo=muscle + cardium=muscle) is the heart muscle that contracts to pump that blood and like any other muscle, it requires oxygen rich blood for energy. Angina...

Torn anterior cruciate ligament (ACL) facts The anterior cruciate ligament is one of the four ligaments in the knee that provides stabilization. Torn ACLs are a common knee injury. An ACL tear or sprain occurs wh...

Antley-Bixler Syndrome is a rare genetic disorder that is primarily characterized by distinctive malformations of the head and facial (craniofacial) area and additional skeletal abnormalities. For example, the disorder is typically associated with...

Introduction to aortic dissection The aorta is the large blood vessel that leads from the heart and carries blood to the rest of the body. It originates at the aortic valve at the outlet of the left ventricle of the heart and ascends withi...

What is aortic stenosis? Aortic stenosis is abnormal narrowing of the aortic valve. A number of conditions cause disease resulting in narrowing of the aortic valve. When the degree of narrowing becomes significant enough to impede the flow...

Aortic stenosis is abnormal narrowing of the aortic valve. A number of conditions cause disease resulting in narrowing of the aortic valve. When the degree of narrowing becomes significant enough to impede the flow of blood from the left ventricle...

The appendix is a small, worm-like appendage attached to the colon. Appendicitis occurs when bacteria invade and infect the wall of the appendix. The most common complications of appendicitis are rupture, abscess, and peritonitis....

Arachnoiditis is a pain disorder caused by the inflammation of the arachnoid, one of the membranes that surround and protect the nerves of the spinal cord. It is characterized by severe stinging, "burning pain", and neurological problems....

What is arsenic? Arsenic is a grey-appearing chemical element (atomic number 33, symbol As in the periodic table) also termed a metalloid. Arsenic can exist in a metallic state in three forms (yellow, black, and gray; with gray predominati...

Attention deficit hyperactivity disorder is a behavioral condition characterized by distractibility, impulsivity, and/or hyperactivity. Although there is no single cause for ADHD, there are a number of biological and social factors ...

Attention deficit hyperactivity disorder (ADHD) is one of the most common chronic disorders affecting school-age children. Current research indicates prevalence rates of 3% to 5% with males being diagnosed with this disorder two and a half times m...

Bacterial vaginosis is an abnormal vaginal condition that is characterized by vaginal discharge and results from an overgrowth of atypical bacteria in the vagina. Bacterial vaginosis is not dangerous, but it can cause disturbing sym...

Balantidiasis is a rare intestinal infection caused by the bacterium, Balantidium coli, a single celled parasite (ciliate protozoan) that frequently infects pigs but on occasion (rarely) infects humans. Some infected people may have no symptoms or...

Batten Turner Type Congenital Myopathy is an extremely rare, inherited muscle disease (myopathy) and is characterized by the lack of muscle tone or floppiness at birth (congenital hypotonia). The symptoms of Batten Turner Type Congenital Myopathy ...

Batten Turner Type Congenital Myopathy is an extremely rare, inherited muscle disease (myopathy) and is characterized by the lack of muscle tone or floppiness at birth (congenital hypotonia). The symptoms of Batten Turner Type Congenital Myopathy ...

Blue rubber bleb nevus syndrome (BRBNS) is a rare blood vessel (vascular) disorder that affects the skin and internal organs of the body. Multiple distinctive skin lesions are usually characteristic of this disorder and are often present at birth ...

Bile duct cancer, also called cholangiocarcinoma, is when unusual cells grow out of control inside your bile ducts. Those are thin tubes about 4 to 5 inches long that move a fluid called bile from your liver to your gallbladder and small intestine...

Bile duct cancer, also called cholangiocarcinoma, is when unusual cells grow out of control inside your bile ducts. Those are thin tubes about 4 to 5 inches long that move a fluid called bile from your liver to your gallbladder and small intestine...

Cyclic vomiting syndrome (CVS) is a rare disorder characterized by recurrent, similar episodes of severe nausea and vomiting. An episode may last for a few hours to several days and then is followed by a period of time during which affected indivi...

Binswanger's disease (BD), also called subcortical vascular dementia, is a type of dementia caused by widespread, microscopic areas of damage to the deep layers of white matter in the brain. The damage is the result of the thickening and narrowing...

What is the bladder? The urinary bladder, or the bladder, is a hollow organ in the pelvis. Most of it lies behind the pubic bone of the pelvis, but when full of urine, it can extend up into the lower part of the abdomen. Its primary functi...

What is the bladder? The urinary bladder, or the bladder, is a hollow organ in the pelvis. Most of it lies behind the pubic bone of the pelvis, but when full of urine, it can extend up into the lower part of the abdomen. Its primary functi...

Female urinary system Your urinary system — which includes the kidneys, ureters, bladder and urethra — is responsible for removing waste from your body through urine. Your kidneys, located toward the back in your upper abdomen,...

Female urinary system Your urinary system — which includes the kidneys, ureters, bladder and urethra — is responsible for removing waste from your body through urine. Your kidneys, located toward the back in your upper abdomen,...

Bladder infection is an infection of the bladder. Bladder infection is also called cystitis and is a type of urinary tract infection (UTI). The urinary tract is naturally sterile and when microbes invade it, an infection may result. The bl...

Bladder infection is an infection of the bladder. Bladder infection is also called cystitis and is a type of urinary tract infection (UTI). The urinary tract is naturally sterile and when microbes invade it, an infection may result. The bl...

Bloom syndrome is a rare genetic disorder characterized by short stature; increased sensitivity to light (photosensitivity); multiple small dilated blood vessels on the face (facial telangiectasia), often resembling a butterfly in shape; immune de...

Bloom syndrome is a rare genetic disorder characterized by short stature; increased sensitivity to light (photosensitivity); multiple small dilated blood vessels on the face (facial telangiectasia), often resembling a butterfly in shape; immune de...

Blue diaper syndrome is a rare, genetic metabolic disorder characterized by the incomplete intestinal breakdown of tryptophan, a dietary nutrient. Symptoms typically include digestive disturbances, fever, irritability and visual difficulties. Some...

Blue rubber bleb nevus syndrome (BRBNS) is a rare blood vessel (vascular) disorder that affects the skin and internal organs of the body. Multiple distinctive skin lesions are usually characteristic of this disorder and are often present at birth ...

The botulism neurotoxin is one of the most potent, lethal substances known. Botulism is a disease caused by this neurotoxin (specifically A, B, E, or F type neurotoxin). The neurotoxin is produced by bacteria called Clostr...

Bowen Hutterite syndrome is a rare genetic disorder that is apparent at birth (congenital). The disorder is characterized by growth delays before birth (intrauterine growth retardation); failure to grow and gain weight at the expected rate (failur...

Brain aneurysm  An aneurysm is a ballooning at a weak spot in an artery wall. An aneurysm's walls can be thin enough to rupture. The illustration shows an individual with an unruptured aneurysm. The inset shows what happens when the a...

What is brain cancer? Brain cancer is a disease of the brain in which cancer cells (malignant cells) arise in the brain tissue. Cancer cells grow to form a mass of cancer tissue (tumor) that interferes with brain functions such as muscle c...

A brain tumor is a mass or growth of abnormal cells in your brain. Many different types of brain tumors exist. Some brain tumors are noncancerous (benign), and some brain tumors are cancerous (malignant). Brain tumors can begin in your bra...

Turcot syndrome is a rare inherited disorder characterized by the association of benign growths (adenomatous polyps) in the mucous lining of the gastrointestinal tract with tumors of the central nervous system. Symptoms associated with polyp forma...

A brain tumor is a mass or growth of abnormal cells in your brain. Many different types of brain tumors exist. Some brain tumors are noncancerous (benign), and some brain tumors are cancerous (malignant). Brain tumors can begin in your bra...

A brain tumor is a mass or growth of abnormal cells in your brain. Many different types of brain tumors exist. Some brain tumors are noncancerous (benign), and some brain tumors are cancerous (malignant). Brain tumors can begin in your bra...

Maple syrup urine disease (MSUD) is a rare genetic disorder characterized by deficiency of certain enzymes (branched-chain alpha-keto acid dehydrogenase complex) required to breakdown (metabolize) specific amino acids in the body. Because these am...

Acrodermatitis enteropathica (AE) is a disorder of zinc metabolism that occurs in one of two forms: an inborn (congenital) form and an acquired form. The inborn form of AE is a rare genetic disorder characterized by intestinal abnormalities that l...

Dengue Fever is an acute viral infection characterized by fever. It is caused by a bite from mosquitoes carrying dengue virus. The primary form of Dengue Fever is characterized by a skin rash and a high fever with severe pain in the head and muscl...

Brief psychotic disorder is in the group of mental illnesses called the schizophrenia spectrum and other psychotic disorders. Symptoms of brief psychotic disorder can include hallucinations or delusions, and they last no longer than...

Bulimia nervosa facts Bulimia is an eating disorder that is characterized by episodes of binging and purging the food and or associated calories. Bulimia is a significant public-health problem, both because of the physical...

Simpson dysmorphia syndrome types 1 and 2 are two forms of a rare, X-linked recessive, inherited disorder characterized by unusually large fetuses (prenatal overgrowth) and unusually large babies (postnatal overgrowth). In addition, affected indiv...

What is metabolic syndrome? Metabolic syndrome is a cluster of metabolic risk factors that come together in a single individual. These metabolic factors include insulin resistance, hypertension (high blood pressure), cholesterol abnormalit...

Familial articular chondrocalcinosis is a rare inherited metabolic disorder characterized by deposits of calcium pyrophosphate dihydrate crystals (CPPD) in one or more joint cartilages resulting in eventual damage to the joints. Symptoms may devel...

Campomelic dysplasia is a severe disorder that affects the development of the skeleton and reproductive system. This condition is often life-threatening in the newborn period. The term "campomelic" comes from the Greek words for "bent limb." Affec...

Campylobacteriosis is an infection caused by bacteria y...

Campylobacteriosis is a bacterial infection caused by Campylobacter bacteria. It is one of the most common causes of foodborne illness in the world, typically contracted through the consumption of contaminated food or water. Symptoms of campylobac...

Pentalogy of Cantrell is a rare disorder that is present at birth (congenital). Pentalogy of Cantrell is characterized by a combination of birth defects. These birth defects can potentially involve the breastbone (sternum), the muscle that separat...

General DiscussionPentalogy of Cantrell is a rare disorder that is present at birth (congenital). Pentalogy of Cantrell is characterized by a combination of birth defects. These birth defects can potentially involve the breastbone (sternu...

Carcinoid syndrome is a disease consisting of a combination of symptoms, physical manifestations, and abnormal laboratory findings. Carcinoid syndrome is seen in individuals who have an underlying carcinoid tumour with spread to the liver. Carcino...

Celiac disease, sometimes called celiac sprue or gluten-sensitive enteropathy, i...

Roussy-Levy Syndrome, also known as hereditary areflexic dystasia, is a rare genetic neuromuscular disorder that typically becomes apparent during early childhood. The disorder is characterized by incoordination, poor judgment of movements (sensor...

Congenital hypomyelination neuropathy (CHN) is a neurological disorder present at birth. Major symptoms may include respiratory difficulty, muscle weakness and incoordination, poor muscle tone (neonatal hypotonia), absence of reflexes (areflexia),...

CHARGE syndrome is a rare disorder that arises during early fetal development and affects multiple organ systems. The term CHARGE comes from the first letter of some of the more common features seen in these children: (C) = coloboma (u...

Budd-Chiari syndrome is a rare disorder characterized by narrowing and obstruction (occlusion) of the veins of the liver (hepatic veins). Symptoms associated with Budd Chiari syndrome include pain in the upper right part of the abdomen, an abnorma...

CHILD syndrome (an acronym for congenital hemidysplasia with ichthyosiform erythroderma and limb defects) is an inherited disorder, affecting primarily women, that is characterized by ichthyosis-like skin abnormalities and limb defects on one side...

Cyclic vomiting syndrome (CVS) is a rare disorder characterized by recurrent, similar episodes of severe nausea and vomiting. An episode may last for a few hours to several days and then is followed by a period of time during which affected indivi...

Giant axonal neuropathy is a rare neuropathy that severely affects the peripheral as well as the central nervous system. The first symptoms appear in early childhood. This disorder is characterized by abnormalities in the peripheral and central ne...

Duchenne muscular dystrophy (DMD) is a rare muscle disorder but it is one of the most frequent genetic conditions affecting approximately 1 in 3,500 male births worldwide. It is usually recognized between three and six years of age. DMD is charact...

Chlamydia is a common sexually transmitted infection (STI) caused by the bacterium Chlamydia trachomatis. It can be transmitted through unprotected sexual contact with an infected person. Chlamydia can infect both men and women and can cause sympt...

Chlamydia is the most commonly reported sexually transmitted disease (STD) in the U.S. It is an infection with the bacteria known as Chlamydia trachomatis. Chlamydia is very similar to gonorrhea in its symptoms and pattern of transmission. It is i...

Cleidocranial dysplasia is a rare skeletal dysplasia characterized by short stature, distinctive facial features and narrow, sloping shoulders caused by defective or absent collarbones (clavicles). Major symptoms may include premature closing of t...

Cleidocranial dysplasia is a rare skeletal dysplasia characterized by short stature, distinctive facial features and narrow, sloping shoulders caused by defective or absent collarbones (clavicles). Major symptoms may include premature closing of t...

Cluster headache is pain that occurs along one side of the head. It's frequently described as pain that occurs around, behind, or above the eye and along the temple in cyclic patterns or clusters. The pain of a cluster headache is very severe. Man...

Congenital hypomyelination neuropathy (CHN) is a neurological disorder present at birth. Major symptoms may include respiratory difficulty, muscle weakness and incoordination, poor muscle tone (neonatal hypotonia), absence of reflexes (areflexia),...

Coffin-Siris syndrome is a rare genetic disorder that may be evident at birth (congenital). The disorder may be characterized by feeding difficulties and frequent respiratory infections during infancy, diminished muscle tone (hypotonia), abnormal ...

Ulcerative colitis is an inflammatory bowel disease (IBD) of unknown cause. It is characterized by chronic inflammation and ulceration of the lining of the major portion of the large intestine (colon). In most affected individuals, the lowest regi...

Collagenous colitis is a rare digestive disorder that primarily affects females and typically becomes apparent during middle age. The disorder is characterized by inflammatory changes of the mucous membranes (mucosa) of the colon (colitis) and abn...

Ulcerative colitis (UL-sur-uh-tiv koe-LIE-tis) is an inflammatory bowel disease ...

Ulcerative colitis (UL-sur-uh-tiv koe-LIE-tis) is an inflammatory bowel disease (IBD) that causes inflammation and ulcers (sores) in your digestive tract. Ulcerative colitis affects the innermost lining of your large intestine (colon) and rectum. ...

Colon cancer Open pop-up dialog box Close Colon cancer Colon cancer Colon cancer can occur in any part of the colon. An examination of your entire colon using a long, flexible tube equipped with a camera (colonoscopy) is one way to detect ...

Colon cancer can occur in any part of the colon. An examination of your entire colon using a long, flexible tube equipped with a camera (colonoscopy) is one way to detect colon cancer and polyps. Colon cancer is a type of cancer that begin...

Freeman-Sheldon syndrome is a rare inherited disorder characterized by multiple contractures (i.e., restricted movement around two or more body areas) at birth (congenital), abnormalities of the head and face (craniofacial) area, defects of the ha...

Crouzon syndrome is a rare genetic disorder that may be evident at birth (congenital) or during infancy. The disorder is characterized by distinctive malformations of the skull and facial (craniofacial) region. Such abnormalities may vary greatly ...

Chromosome 22q11.2 deletion syndrome is associated with a range of problems including: congenital heart disease, palate abnormalities, immune system dysfunction including autoimmune disease, low calcium (hypocalcemia) and other endocrine abnormali...

Craniofrontonasal dysplasia is a very rare inherited disorder characterized by abnormalities of the head and face (craniofacial area), hands and feet, and certain skeletal bones. Major symptoms of this disorder may include widely spaced eyes (ocul...

Creutzfeldt-Jakob disease (CJD) is a rare, degenerative, invariably fatal brain disorder. It affects about one person in every one million people per year worldwide; in the United States there are about 200 cases per year. CJD usually appears in l...

Adenoid cystic carcinoma (ACC) is a relatively rare form of cancer that most commonly develops in the salivary glands or other regions of the head and neck. In some cases, ACC may arise in other primary sites, such as the skin; the breast; the nec...

Crohn's disease facts Crohn's disease is a chronic inflammatory disease of the intestines. The cause of Crohn's disease is unknown. Crohn's disease can cause ulcers in the small intestine, colon, or both. ...

Cronkhite-Canada syndrome (CCS) is a very rare disease with symptoms that include loss of taste, intestinal polyps, hair loss, and nail growth problems. It is difficult to treat because of malabsorption that accompanies the polyps. CCS occurs prim...

Mixed cryoglobulinemia is a rare disorder characterized by the presence of cryoglobulins in the blood. Cryoglobulins are abnormal proteins that thicken and clump together at cold temperatures, usually below 98.6 degrees Fahrenheit (the average hum...

Fraser syndrome is a rare genetic disorder characterized by partial webbing of the fingers and/or toes (partial syndactyly), kidney (renal) abnormalities, genital malformations, and/or, in some cases, complete fusion of the eyelids (cryptophthalmo...

Cryptosporidiosis is a diarrheal disease caused by microscopic parasites, Cryptosporidium, that can live in the intestine of humans and animals and is passed in the stool of an infected person or animal. Both the disease and the parasite are commo...

Cryptosporidiosis is a parasitic infection caused by the Cryptosporidium parasite. It is typically transmitted through contaminated water or food, or through contact with infected animals or people. Symptoms of cryptosporidiosis include diarrhea, ...

Common Variable Immune Deficiency (CVID) is a type of primary immunodeficiency, which is defined as an immune system dysfunction typically caused by a mutation in a gene or genes. The World Health Organization (WHO) recognizes more than 150 primar...

  Cyclic vomiting syndrome is a disorder that causes recurrent episodes of nausea, vomiting, and tiredness (lethargy) most often in children but may occur in all age groups. Symptoms of cyclic vomiting syndrome are re...

Cyclic vomiting syndrome is characterized by episodes of severe vomiting that ha...

Cyclospora infection (cyclosporiasis) facts Cyclospora is a small parasitic organism that is passed to humans when they ingest food contaminated with feces from an infected person. It is most common in tropical countries, ...

Autosomal dominant interstitial kidney disease describes a group of diseases affecting solely the proper function of the kidney and having the following characteristics: They are inherited in an autosomal dominant manner; kidney disease develops, ...

Autosomal dominant interstitial kidney disease describes a group of diseases affecting solely the proper function of the kidney and having the following characteristics: They are inherited in an autosomal dominant manner; kidney disease develops, ...

Cystinuria facts Cystinuria is a relatively common inherited disorder. The disorder is due to a defect in the transport of amino acids including one called cystine. Cystinuria features too much cystine in the uri...

A cystocele occurs when the wall between a woman's bladder and her vagina weakens and allows the bladder to droop into the vagina. Symptoms of a cystocele include urine leakage and incomplete emptying of the bladder. Cause...

Autosomal dominant interstitial kidney disease describes a group of diseases affecting solely the proper function of the kidney and having the following characteristics: They are inherited in an autosomal dominant manner; kidney disease develops, ...

General DiscussionCytochrome C Oxidase deficiency is a very rare inherited metabolic disorder characterized by deficiency of the enzyme cytochrome C oxidase (COX), or Complex IV, an essential enzyme that is active in the subcellular struc...

Keratosis follicularis, also known as Darier disease, is a rare, genetic skin disorder. Affected individuals develop skin lesions that consist of thickened, rough bumps (papules) or plaques that may also be greasy or have a brown or yellow crust. ...

Microvillus inclusion disease is an extremely rare inherited intestinal disorder (enteropathy) that is typically apparent within hours or days after birth. The disorder is characterized by chronic, severe, watery diarrhea and insufficient absorpti...

Degos disease is an extremely rare disorder in which small and medium sized arteries become blocked (occlusive arteriopathy), restricting the flow of blood to affected areas. Degos disease usually causes characteristic skin lesions that may last f...

Degos disease is an extremely rare disorder in which small and medium sized arteries become blocked (occlusive arteriopathy), restricting the flow of blood to affected areas. Degos disease usually causes characteristic skin lesions that may last f...

Dehydration facts The body needs water to function. Dehydration occurs when water intake is less than water loss. Symptoms range from mild to life-threatening. The young and the elderly are especially s...

Dental fluorosis is a condition that affects the teeth due to overexposure to fluoride during the early years of life. It can cause white or brown spots, streaks, or pits on the teeth, and in severe cases, it can lead to enamel erosion and discolo...

Dentinogenesis Imperfecta is a genetic disorder that affects the development of tooth dentin, which is the hard tissue that makes up the majority of a tooth. This condition results in teeth that are discolored, weak, and prone to breaking or weari...

Determining hearing loss in children facts Children can be tested for hearing loss at any age. There are several risk factors associated with hearing loss, including ear infections, prematurity, diseases, and syndromes....

Diabetes facts Diabetes is a chronic condition associated with abnormally high levels of sugar (glucose) in the blood. Insulin produced by the pancreas lowers blood glucose. Absence or insufficient production of ...

Diabetes and foot problems facts Two main conditions, peripheral artery disease (PAD) and peripheral neuropathy, are responsible for the increased risk of foot problems in people with diabetes. People with diabetes have an...

What is the difference between diabetes insipidus and diabetes mellitus Diabetes insipidus should not be confused with diabetes mellitus (DM), which results from insulin deficiency or resistance leading to high blood glucose, also called b...

What is the difference between diabetes insipidus and diabetes mellitus Diabetes insipidus should not be confused with diabetes mellitus (DM), which results from insulin deficiency or resistance leading to high blood glucose, also called b...

Nephrogenic diabetes insipidus (NDI) is a rare kidney disorder that may be inherited or acquired. NDI is not related to the more common diabetes mellitus (sugar diabetes), in which the body does not produce or properly use insulin. NDI is a distin...

Nephrogenic diabetes insipidus (NDI) is a rare kidney disorder that may be inherited or acquired. NDI is not related to the more common diabetes mellitus (sugar diabetes), in which the body does not produce or properly use insulin. NDI is a distin...

Type 2 diabetes is an impairment in the way the body regulates and uses sugar (g...

Achard-Thiers syndrome is a rare disorder that occurs primarily in postmenopausal women and is characterized by type 2 (insulin-resistant) diabetes mellitus and signs of androgen excess. The exact cause of this syndrome is unknown....

Diabetic ketoacidosis is a serious complication of diabetes that occurs when you...

Diabetic ketoacidosis is a serious complication of diabetes that occurs when you...

Dislocated ankle facts An isolated dislocated ankle is a rare injury. Usually, there is an associated fracture of the bones that make up the ankle. The ankle dislocates as a result of a fall, motor-vehicle crash, or sporti...

Diverticulosis and diverticulitis facts Most patients with diverticulosis (diverticular disease) have few or no symptoms. Abdominal pain, constipation, and diarrhea, can occur with diverticulosis, which then may be called ...

Dyggve-Melchior-Clausen (DMC) syndrome is a rare, progressive genetic disorder characterized by abnormal skeletal development, microcephaly and intellectual disability. The condition was first reported by Dyggve, Melchior and Clausen in 1962 in th...

Dyggve-Melchior-Clausen (DMC) syndrome is a rare, progressive genetic disorder characterized by abnormal skeletal development, microcephaly and intellectual disability. The condition was first reported by Dyggve, Melchior and Clausen in 1962 in th...

Harlequin ichthyosis is a rare genetic skin disorder. The newborn infant is covered with plates of thick skin that crack and split apart. The thick plates can pull at and distort facial features and can restrict breathing and eating. Harlequin inf...

DOOR syndrome is a rare genetic disorder that may be recognized shortly after birth. "DOOR," an acronym for characteristic abnormalities associated with the syndrome, stands for (D)eafness due to a defect of the inner ear or auditory nerve (sensor...

Trismus-Pseudocamptodactyly Syndrome is a very rare inherited disorder characterized by the inability to completely open the mouth (trismus), causing difficulty with chewing (mastication) and/or the presence of abnormally short muscle-tendon units...

Dyskeratosis congenita is a rare genetic form of bone marrow failure, the inability of the marrow to produce sufficient blood cells. Dyskeratosis is Latin and means the irreversible degeneration of skin tissue, and congenita means inborn. First de...

Dyskeratosis congenita is a rare genetic form of bone marrow failure, the inability of the marrow to produce sufficient blood cells. Dyskeratosis is Latin and means the irreversible degeneration of skin tissue, and congenita means inborn. First de...

Dyskeratosis congenita is a rare genetic form of bone marrow failure, the inability of the marrow to produce sufficient blood cells. Dyskeratosis is Latin and means the irreversible degeneration of skin tissue, and congenita means inborn. First de...

Dyskeratosis congenita is a rare genetic form of bone marrow failure, the inability of the marrow to produce sufficient blood cells. Dyskeratosis is Latin and means the irreversible degeneration of skin tissue, and congenita means inborn. First de...

Escherichia coli (E. coli) bacteria normally live in the intestines of healthy people and animals. Most varieties of E. coli are harmless or cause relatively brief diarrhea. But a few particularly nasty strains, such as E. coli O157:H7, can cause ...

E. coli infection is a type of bacterial infection caused by the bacterium Escherichia coli. E. coli bacteria are commonly found in the intestines of humans and animals, and most strains are harmless. However, some strains of E. coli can cause ill...

Rapp-Hodgkin syndrome, an extremely rare inherited multisystem disorder that is apparent at birth (congenital) or during infancy, belongs to a group of diseases known as ectodermal dysplasias. Ectodermal dysplasias typically affect the skin, teeth...

Johanson-Blizzard syndrome (JBS) is an extremely rare genetic disorder that affects multiple organ systems of the body. Many symptoms are present at birth (congenital) or early childhood. The spectrum of potential features and physical findings as...

An ectopic pregnancy is a pregnancy located outside the inner lining of the uterus. Risk factors for ectopic pregnancy include previous ectopic pregnancies and conditions (surgery, infection) that disrupt the normal anatomy of the F...

Ectrodactyly ectodermal dysplasia cleft lip/palate (EEC) syndrome is a rare genetic disorder. Symptoms can vary greatly from one person to another. Affected individuals often have abnormalities affecting the limbs including ectrodactyly, a conditi...

Encephalitis (en-sef-uh-LIE-tis) is inflammation of the brain. There are several causes, including viral infection, autoimmune inflammation, bacterial infection, insect bites and others. Sometimes there is no known cause. Encephalitis may ...

Japanese Encephalitis is a severe inflammation of the brain caused by the Japanese B Encephalitis Virus that is transmitted by the bite of infected mosquitoes in certain areas of the world, particularly Asia. This disorder most commonly affects ch...

Pancreatic neuroendocrine neoplasms (pNENs) are an increasingly common group of malignancies that arise within the endocrine tissue of the pancreas. Endocrine tissue is specialized tissue that contains hormone-secreting cells. These cells secrete ...

Atrioventricular septal defect (ASVD) is a general term for a group of rare heart defects that are present at birth (congenital). Infants with ASVDs have improperly developed atrial and ventricular septa and adjoining valves. The norma...

Endometrial ablation facts Endometrial ablation is the surgical destruction of the lining tissues of the uterus. Endometrial ablation is one type of treatment for abnormal uterine bleeding that is due to a benign (non-canc...

Endometriosis is the abnormal growth of cells (endometrial cells) similar to those that form the inside of the uterus, but in a location outside of the uterus. Endometriosis is most commonly found on other organs of the pelvis. The ...

Enterovirulent E. coli (EEC) facts Enterovirulent E. coli (EEC) are bacteria that comprise several groups of E. coli serovars, all of which may cause diarrhea and other problems in the intestines. EEC bacteria can cause a ...

Epidermal nevus syndromes (ENSs) are a group of rare complex disorders characterized by the presence of skin lesions known as epidermal nevi associated with additional extra-cutaneous abnormalities, most often affecting the brain, eye and skeletal...

Epidermolysis bullosa (ep-ih-dur-MOL-uh-sis buhl-LOE-sah) is a group of rare diseases that cause fragile, blistering skin. The blisters may appear in response to minor injury, even from heat, rubbing, scratching or adhesive tape. In severe cases, ...

Epidermolysis bullosa (EB) is a genetic skin disorder characterized clinically by blister formation from mechanical trauma. There are four main types with additional sub-types identified. There is a spectrum of severity, and within each type, one ...

Epidermolysis bullosa (EB) is a genetic skin disorder characterized clinically by blister formation from mechanical trauma. There are four main types with additional sub-types identified. There is a spectrum of severity, and within each type, one ...

Epidermolysis bullosa (EB) is a genetic skin disorder characterized clinically by blister formation from mechanical trauma. There are four main types with additional sub-types identified. There is a spectrum of severity, and within each type, one ...

The largest part of the brain, the cerebrum, is divided into four paired sections -- the frontal, parietal, occipital, and temporal lobes. Each lobe controls a specific group of activities. The temporal lobe, located on either side of the brain ju...

The largest part of the brain, the cerebrum, is divided into four paired sections -- the frontal, parietal, occipital, and temporal lobes. Each lobe controls a specific group of activities. The temporal lobe, located on either side of the brain ju...

The hereditary ataxias are a group of neurological disorders (ataxias) of varying degrees of rarity that are inherited, in contrast to a related group of neurological disorders that are acquired through accidents, injuries, or other external agent...

General DiscussionCongenital rubella is a syndrome that occurs when a fetus has been infected with the rubella virus while in the uterus. It is primarily characterized by abnormalities of the heart and nervous system, the eyes and the ear...

Fabry disease is caused by the lack of or faulty enzyme needed to metabolize lipids, fat-like substances that include oils, waxes, and fatty acids. The enzyme is known as ceramide trihexosidase, also called alpha-galactosidase-A. A mutation in the...

Cardiofaciocutaneous (CFC) syndrome is one of the RASopathies and is a rare genetic disorder is typically characterized by unusually sparse, brittle, curly hair; large head (macrocephaly); a prominent forehead and abnormal narrowing of the sides o...

Facioscapulohumeral muscular dystrophy (FSHD), also known as Landouzy-Dejerine muscular dystrophy, is a neuromuscular disorder. Symptom onset usually occurs in adolescence or early adulthood; however, less commonly, symptoms may become apparent as...

Familial lipoprotein lipase (LPL) deficiency is a rare genetic metabolic disorder characterized by a deficiency of the enzyme lipoprotein lipase. The deficiency of this enzyme prevents affected individuals from properly digesting certain fats and ...

Febrile seizures are convulsions brought on by a fever in infants or small children. How common are febrile seizures? Approximately one in every 25 children will have at least one febrile seizure, and more than one-third of these c...

Coffin-Siris syndrome is a rare genetic disorder that may be evident at birth (congenital). The disorder may be characterized by feeding difficulties and frequent respiratory infections during infancy, diminished muscle tone (hypotonia), abnormal ...

Fitz-Hugh-Curtis syndrome is a rare disorder that occurs almost exclusively in women. It is characterized by inflammation of the membrane lining the stomach (peritoneum) and the tissues surrounding the liver (perihepatitis). The muscle that separa...

Fraser syndrome is a rare genetic disorder characterized by partial webbing of the fingers and/or toes (partial syndactyly), kidney (renal) abnormalities, genital malformations, and/or, in some cases, complete fusion of the eyelids (cryptophthalmo...

Friedreich's Ataxia is a genetic, progressive, neurologic movement disorder that typically becomes apparent before adolescence. Initial symptoms may include unsteady posture, frequent falling, and progressive difficulties walking due to an impaire...

Chiari-Frommel Syndrome is a rare endocrine disorder that affects women who have recently given birth (postpartum) and is characterized by the over-production of breast milk (galactorrhea), lack of ovulation (anovulation), and the absence of regul...

Frontotemporal dementia (FTD), or Pick's disease, is a syndrome featuring shrinking of the frontal and temporal anterior lobes of the brain. The symptoms of frontotemporal dementia fall into two clinical patterns that involve either...

  Frontotemporal dementia (FTD), or Pick's disease, is a syndrome featuring shrinking of the frontal and temporal anterior lobes of the brain. The symptoms of frontotemporal dementia fall into two clinical patterns th...

The word "neurasthenia" is a term that has fallen into disuse among psychiatrists in the United States and Australia. It remains in use in the United Kingdom. Where it is used, it covers a wide spectrum of symptoms including the sensation of pain ...

Glucose-6-Phosphate Dehydrogenase (G6PD) Deficiency (G6PDD) is an inherited, sex-linked, metabolic disorder characterized by an enzyme defect that leads to the breakdown of red blood cells (hemolysis) upon exposure to stresses associated with some...

A prolactinoma is a benign tumor of the pituitary gland (adenoma) that produces an excessive amount of the hormone prolactin. In women, hyperprolactinemia is characterized by irregular menstrual periods (amenorrhea), infertility and production of ...

Ahumada-Del Castillo is a rare endocrine disorder affecting adult females, which is characterized by impairment in the function of the pituitary and hypothalamus glands. Symptoms may include the production of breast milk (lactation) not associated...

Schindler disease is a rare inherited metabolic disorder characterized by the deficient activity of the lysosomal enzyme alpha-N-acetylgalactosaminidase (alpha-NAGA or alpha-galactosidase B). The enzyme defect leads to the abnormal accumulation of...

Mucolipidosis IV is a rare inherited metabolic disorder believed to be characterized by a deficiency of transport channel receptor protein, based upon the recent discovery of the Mucolipidosis IV gene. This deficiency may lead to the accumulation ...

Gastritis is inflammation of the lining of the stomach. Unfortunately, the term "gastritis" has been misused to include many different upper abdominal problems, but true gastritis refers to the stomach lining (gastric mucosa) that is inflamed. All...

Definition of gastroenteritis Gastroenteritis (often referred to as the "stomach flu," however, it is not related to the influenza virus. Gastroenteritis is a nonspecific term for various inflammatory problems in the gastrointestinal tract...

Gaucher disease is an inherited disorder of metabolism that interferes with many body functions. There are different forms of Gaucher disease. The perinatal lethal form is the most severe type of Gaucher disease. ...

Genital herpes is a sexually transmitted disease caused by herpes simplex virus (HSV). HSV causes genital herpes by entering the skin or mucous membranes through microscopic breaks in the skin and mucous membranes. Genital...

Genital warts (HPV) facts Genital warts are caused by infection with a subgroup of the human papillomaviruses (HPVs). Another subgroup of the HPVs that infect the anogenital tract can lead to precancerous changes in the ut...

Gestational diabetes is diabetes, or high blood sugar levels, that develops during pregnancy. It occurs in about 4% of all pregnancies. It is usually diagnosed in the later stages of pregnancy and often occurs in women who have never had diabetes....

Giardiasis is a common intestinal infection caused by a microscopic parasite called Giardia lamblia. It is typically contracted by ingesting contaminated food or water, and can cause symptoms such as diarrhea, abdominal cramps, bloating, and weigh...

Aniridia, cerebellar ataxia, and mental deficiency, also known as Gillespie syndrome, is an extremely rare inherited disorder that is characterized by the absence, in whole (aniridia) or in part (partial aniridia), of the colored portion (iris) of...

Glaucoma is a disease that is often associated with elevated intraocular pressure, in which damage to the eye (optic) nerve can lead to loss of vision and even blindness. Glaucoma is the leading cause of irreversible blindness in th...

Turcot syndrome is a rare inherited disorder characterized by the association of benign growths (adenomatous polyps) in the mucous lining of the gastrointestinal tract with tumors of the central nervous system. Symptoms associated with polyp forma...

Pierre Robin sequence is characterized by an unusually small lower jaw (micrognathia) and downward displacement of the tongue (glossoptosis). Some infants also have an abnormal opening in the roof of the mouth (cleft palate); both the soft and har...

Glucose-galactose malabsorption is an inherited metabolic disorder characterized by the small intestine's inability to transport and absorb glucose and galactose (simple sugars or monosaccharides). Glucose and galactose have very similar chemical ...

General DiscussionGlutaricaciduria II is one of the conditions termed organic acidemias. Individuals with these conditions have a deficiency or absence of an enzyme that prevents them from breaking down certain chenicals in the body, resu...

Glutaricaciduria II is one of the conditions termed organic acidemias. Individuals with these conditions have a deficiency or absence of an enzyme that prevents them from breaking down certain chenicals in the body, resulting the accumulation of s...

Glutaricaciduria II is one of the conditions termed organic acidemias. Individuals with these conditions have a deficiency or absence of an enzyme that prevents them from breaking down certain chenicals in the body, resulting the accumulation of s...

Fabry disease is a rare genetic disorder of fat (lipid) metabolism characterized by a deficiency of the enzyme alpha-galactosidase A (previously known as ceramide trihexosidase). The disorder belongs to a group of diseases known as lysosomal stora...

Gonorrhea is a sexually transmitted infection (STI) caused by the bacterium Neisseria gonorrhoeae. It can infect both men and women and is most commonly spread through unprotected sexual contact. Symptoms of gonorrhea can include painful urination...

Gonorrhea is a bacterial infection that is transmitted during sexual activity. Gonorrhea is not transmitted from toilet seats. Women infected with gonorrhea may not have any symptoms. Gonorrhea is treated with an...

Metachromatic leukodystrophy, the most common form of leukodystrophy, is a rare inherited neurometabolic disorder affecting the white matter of the brain (leukoencephalopathy). It is characterized by the accumulation of a fatty substance known as ...

SHORT syndrome is a condition in which affected individuals have multiple birth defects in different organ systems. The term SHORT is an acronym with each letter representing one of the common findings in affected persons:(S)= short st...

Lichen sclerosus is a chronic skin disorder that most commonly affects post-menopausal women. However, it is sometimes identified among pre-menopausal women, and, even more rarely, among males. When found in males, the disease is known as balaniti...

Congenital central hypoventilation syndrome (CCHS) is a rare disorder of respiratory control with autonomic nervous system dysregulation (ANSD). The autonomic nervous system is the portion of the nervous system that controls or regulates certain i...

Histidinemia is a rare hereditary metabolic disorder characterized by a deficiency of the enzyme histidase, which is necessary for the metabolism of the amino acid histidine. The concentration of histidine is elevated in the blood. Excessive amoun...

Pallister-Hall syndrome (PHS) is an extremely rare genetic disorder that is typically apparent at birth. The symptoms and findings associated with the disorder may vary greatly in range and severity from patient to patient. However, in many indivi...

Epidermolysis bullosa (EB) is a genetic skin disorder characterized clinically by blister formation from mechanical trauma. There are four main types with additional sub-types identified. There is a spectrum of severity, and within each type, one ...

Vogt-Koyanagi-Harada disease is a rare disorder of unknown origin that affects many body systems, including as the eyes, ears, skin, and the covering of the brain and spinal cord (the meninges). The most noticeable symptom is a rapid loss of visio...

Paroxysmal cold hemoglobinuria (PCH) is a rare type of anemia characterized by the premature destruction of healthy red blood cells by autoantibodies. The disorder is classified as an autoimmune hemolytic anemia (AIHA), an uncommon group of disord...

Hartnup disease is a rare metabolic disorder inherited as an autosomal recessive trait. It involves an inborn error of amino acid metabolism as well as niacin deficiency. Factors that may precipitate acute attacks of this disorder may include poor...

Hartnup disease is a rare metabolic disorder inherited as an autosomal recessive trait. It involves an inborn error of amino acid metabolism as well as niacin deficiency. Factors that may precipitate acute attacks of this disorder may include poor...

Hay-Wells syndrome, also known as ankyloblepharon-ectodermal dysplasia-clefting (AEC) syndrome, is a rare inherited disorder that belongs to a group of disorders known as the ectodermal dysplasias. Major characteristics of Hay-Wells syndrome inclu...

What Is Restrictive Cardiomyopathy? Restrictive cardiomyopathy, the rarest form of cardiomyopathy, is a condition in which the walls of the lower chambers of the heart (the ventricles) are abnormally rigid and lack the flexibility to expan...

Restrictive cardiomyopathy, the rarest form of cardiomyopathy, is a condition in which the walls of the lower chambers of the heart (the ventricles) are abnormally rigid and lack the flexibility to expand as the ventricles fill with blood. ...

What Is a Biventricular Pacemaker? Leads are implanted through a vein into the right ventricle and into the coronary sinus vein to pace or regulate the left ventricle. Usually (but not always), a lead is also implanted into the right atriu...

What Is a Biventricular Pacemaker? Leads are implanted through a vein into the right ventricle and into the coronary sinus vein to pace or regulate the left ventricle. Usually (but not always), a lead is also implanted into the right atriu...

Introduction to heart transplant The idea of replacing a bad organ with a good one has been documented in ancient mythology. The first real organ transplants were probably skin grafts that may have been done in India as early as the second...

Helicobacter pylori (H. pylori) facts Helicobacter pylori (H. pylori) is a bacterium that causes chronic inflammation in the stomach and is a common cause of ulcers worldwide H. pylori causes chronic inflammation (gastriti...

Hemolytic uremic syndrome (HUS) is a condition caused by the abnormal destruction of red blood cells. The damaged red blood cells clog the filtering system in the kidneys, which can lead to life-threatening kidney failure. HUS usually deve...

Hepatitis A is a highly contagious liver infection caused by the hepatitis A virus. It is typically spread through contaminated food or water, or through close contact with an infected person. Symptoms of hepatitis A can include fever, fatigue, lo...

Hepatitis B is a viral infection that attacks the liver and can cause both acute and chronic disease. The virus is transmitted through contact with the blood or other body fluids of an infected person. Hepatitis B can be a mild illness lasting a f...

Hepatitis C is a viral infection that causes liver inflammation, sometimes leading to serious liver damage. The hepatitis C virus (HCV) is spread through contact with infected blood, most commonly through sharing needles or other equipment used to...

Hepatitis D, also known as delta hepatitis, is a liver infection caused by the hepatitis D virus (HDV). HDV is a small, defective RNA virus that can only replicate in the presence of the hepatitis B virus (HBV). This means that a person can only g...

Hepatitis E is a liver infection caused by the hepatitis E virus (HEV). It is typically a self-limiting illness that resolves on its own within a few weeks. However, in some cases, it can cause acute liver failure, especially in pregnant women and...

Hepatorenal syndrome (HRS) is a form of impaired kidney function that occurs in individuals with advanced liver disease. Individuals with hepatorenal syndrome do not have any identifiable cause of kidney dysfunction and the kidneys themselves are ...

Roussy-Levy Syndrome, also known as hereditary areflexic dystasia, is a rare genetic neuromuscular disorder that typically becomes apparent during early childhood. The disorder is characterized by incoordination, poor judgment of movements (sensor...

Hereditary spherocytic hemolytic anemia is a rare blood disorder characterized by defects within red blood cells (intracorpuscular) that result in a shortened survival time for these cells. Red blood cells (erythrocytes) normally circulate for a f...

The esophagus connects the mouth and throat to the stomach. It passes through the chest cavity and enters the abdominal cavity through a hole in the diaphragm called the esophageal hiatus. The term hiatal hernia describes a condition where a part ...

Hidradenitis suppurativa (HS) is a chronic condition characterized by swollen, painful lesions, occurring in the armpit (axillae), groin, anal, and breast regions. This disease occurs due to obstruction of hair follicles and secondary infection an...

Hidradenitis suppurativa (hi-drad-uh-NIE-tis sup-yoo-ruh-TIE-vuh) is rare, long-term skin condition that features small, painful lumps under the skin. They typically develop where the skin rubs together, such as the armpits, the groin, between the...

Tropical Sprue is a rare digestive disease in which the small intestine's ability to absorb nutrients is impaired (malabsorption). Consequently, nutritional deficiencies and abnormalities in the mucous lining of the small intestine may be present....

Von Hippel-Lindau syndrome (VHL) is an autosomal dominant genetic disorder characterized by the abnormal growth of blood vessels in certain parts of the body (angiomatosis). Very small blood vessels (capillaries) "knot" together to form benign gro...

Kikuchi's disease, also known as histiocytic necrotizing lymphadenopathy, is a rare, benign, (noncancerous, nonmalignant) disorder of the lymph nodes of young adults, predominantly in young women. This disorder is often mistaken for malignant lymp...

Langerhans cell histiocytosis (LCH) is a spectrum of rare disorders characterized by overproduction (proliferation) and accumulation of a specific type of white blood cell (histiocyte) in the various tissues and organs of the body (lesions). The l...

Papular urticaria, usually called hives, is characterized by large numbers of very itchy red bumps (papules) that come and go every few days over a period of a month or so. The bumps are usually between 0.2 and 2 cm. in size and some may develop i...

Homocysteine is an amino acid that is produced by the body by chemically altering adenosine. Amino acids are naturally made products, which are the building blocks of all the proteins in the body.  ...

Human Papillomavirus (HPV) is a group of viruses that can infect the skin and mucous membranes of humans. There are over 100 different types of HPV, some of which can cause genital warts and others that can lead to various types of cancer, includi...

Bowen Hutterite syndrome is a rare genetic disorder that is apparent at birth (congenital). The disorder is characterized by growth delays before birth (intrauterine growth retardation); failure to grow and gain weight at the expected rate (failur...

Bartter's syndrome (BS) is a group of conditions involving enlargement of certain kidney cells, blood that is more alkaline than normal, high levels of potassium and chloride in the urine, loss of potassium from the kidneys (renal potassium wastin...

Bartter's syndrome (BS) is a group of conditions involving enlargement of certain kidney cells, blood that is more alkaline than normal, high levels of potassium and chloride in the urine, loss of potassium from the kidneys (renal potassium wastin...

Williams syndrome, also known as Williams-Beuren syndrome, is a rare genetic disorder characterized by growth delays before and after birth (prenatal and postnatal growth retardation), short stature, a varying degree of mental deficiency, and dist...

Familial lipoprotein lipase (LPL) deficiency is a rare genetic metabolic disorder characterized by a deficiency of the enzyme lipoprotein lipase. Deficiency of this enzyme prevents affected individuals from properly digesting certain fats and resu...

High blood sugar (hyperglycemia) affects people who have diabetes. Several facto...

Ichthyosis hystrix, Curth-Macklin type is a rare inherited skin disorder. It is characterized by scaling skin (ichthyosis) ranging from mild to severe. The patches of scaly, thickened skin range from spotty to severe, and may appear on almost any ...

Keratosis follicularis spinulosa decalvans (KFSD) is a rare, inherited, skin disorder that affects men predominately and is characterized by hardening of the skin (keratosis) in several parts of the body. Most frequently, the face, neck, and forea...

Sjogren-Larsson syndrome is an inherited disorder characterized by scaling skin (ichthyosis), mental retardation, speech abnormalities, and spasticity. Affected infants develop various degrees of reddened skin with fine scales soon after birth. Af...

Ichthyosis vulgaris (ik-thee-O-sis vul-GAY-ris) is an inherited skin disorder in which dead skin cells accumulate in thick, dry scales on your skin's surface. The scales of ichthyosis vulgaris, sometimes called fish scale disease or fish s...

Chanarin Dorfman syndrome is a rare hereditary disorder of fat (lipid) metabolism. It is characterized by scaly skin (ichthyosis), degeneration of the muscles (myopathy), and abnormal white blood cells with small spaces (vacuoles) filled with fat ...

Androgen insensitivity refers to an inability of the body to respond properly to male sex hormones (androgens) produced during pregnancy. This occurs because of a change (mutation) in a gene involved in the production of the protein inside cells t...

Dyspepsia (indigestion) facts Dyspepsia is a functional disease in which the gastrointestinal organs, primarily the stomach and first part of the small intestine, function abnormally. It is a chronic disease in which the symptoms fl...

Santavuori disease, a rare genetic disorder, belongs to a group of progressive degenerative neurometabolic diseases known as the neuronal ceroid lipofuscinoses (NCL). These disorders share certain similar symptoms and are distinguished in part by ...

The spinal muscular atrophies (SMAs), are characterized by degeneration of nerve cells (motor nuclei) within the lowest region of the brain (lower brainstem) and certain motor neurons in the spinal cord (anterior horn cells) leading to muscle weak...

Santavuori disease, a rare genetic disorder, belongs to a group of progressive degenerative neurometabolic diseases known as the neuronal ceroid lipofuscinoses (NCL). These disorders share certain similar symptoms and are distinguished in part by ...

Sydenham chorea is a rare neurological disorder characterized by rapid, involuntary, purposeless movements, especially of the face, feet and hands. Additional symptoms may include muscle weakness and emotional or behavioral problems. Sydenham chor...

Infertility means not being able to become pregnant, within certain parameters. Infertility is a common problem of about 10% of women aged 15 to 44. Infertility can be due to the woman (33%), the man (33%) and by both sexe...

Influenza, commonly known as the flu, is a contagious respiratory illness caused by influenza viruses. It can cause mild to severe illness and can sometimes lead to hospitalization or even death. Symptoms of the flu include fever, cough, sore thro...

Insulin is a hormone that is produced by the beta cells of the pancreas. These cells are scattered throughout the pancreas in small clusters known as the islets of Langerhans. The insulin produced is released into the blood stream and travels thro...

Interstitial cystitis facts PBS/IC is an inflammatory disease of the bladder that can cause ulceration and bleeding of the bladder's lining and can lead to scarring and stiffening of the bladder. The symptoms of PBS/IC are...

Intussusception facts Intussusception is the infolding (telescoping) of one segment of the intestine within another. Intussusception usually results in a blockage of the intestine. Intussusception occurs primaril...

What is the definition of irritable bowel syndrome (IBS)? Irritable bowel syndrome (IBS) is a gastrointestinal disorder characterized by the presence of a cluster of symptoms and signs in adult or children that include cramping, abdominal ...

What is irritable bowel syndrome (IBS)? Irritable bowel syndrome is a functional gastrointestinal (GI) disorder, meaning it is a problem caused by changes in how the GI tract works. Children with a functional GI disorder have frequent symp...

General DiscussionIvemark syndrome is a rare disorder that affects multiple organ systems of the body. It is characterized by the absence (asplenia) or underdevelopment (hypoplasia) of the spleen, malformations of the heart and the abnorm...

Creutzfeldt-Jakob disease (CJD) is an extremely rare degenerative brain disorder (i.e., spongiform encephalopathy) characterized by sudden development of rapidly progressive neurological and neuromuscular symptoms. With symptom onset, affected ind...

Creutzfeldt-Jakob disease (CJD) is an extremely rare degenerative brain disorder (i.e., spongiform encephalopathy) characterized by sudden development of rapidly progressive neurological and neuromuscular symptoms. With symptom onset, affected ind...

wJansen type metaphyseal chondrodysplasia is an extremely rare progressive disorder in which portions of the bones of the arms and legs develop abnormally with unusual cartilage formations and subsequent abnormal bone formation at the large (bulbo...

Jansen type metaphyseal chondrodysplasia is an extremely rare progressive disorder in which portions of the bones of the arms and legs develop abnormally with unusual cartilage formations and subsequent abnormal bone formation at the large (bulbou...

Jarcho-Levin syndrome is a rare genetic disorder characterized by distinctive malformations of bones of the spinal column (vertebrae) and the ribs, respiratory insufficiency, and/or other abnormalities. Infants born with Jarcho-Levin syndrome have...

X-linked juvenile retinoschisis (RS) is a genetic disorder affecting males. Major symptoms include poor eyesight and degeneration of the retina. The retina consists of membrane layers in the eye that receive visual images. It is composed of suppor...

Bartter's syndrome (BS) is a group of conditions involving enlargement of certain kidney cells, blood that is more alkaline than normal, high levels of potassium and chloride in the urine, loss of potassium from the kidneys (renal potassium wastin...

A keloid scar forms from abnormal healing, and usually develops in people 10 to 20 years old. A keloid, or keloid scar, is a kind of overgrown scar, or an overly aggressive healing response to a wound. It's a type of thick, irregul...

Kenny-Caffey syndrome type 2 (KCS2) is an extremely rare hereditary skeletal disorder characterized by thickening of the long bones, thin marrow cavities in the bones (medullary stenosis), and abnormalities affecting the head and eyes. Most cases ...

Kenny-Caffey syndrome type 2 (KCS2) is an extremely rare hereditary skeletal disorder characterized by thickening of the long bones, thin marrow cavities in the bones (medullary stenosis), and abnormalities affecting the head and eyes. Most cases ...

Epidermolysis bullosa (EB) is a genetic skin disorder characterized clinically by blister formation from mechanical trauma. There are four main types with additional sub-types identified. There is a spectrum of severity, and within each type, one ...

Keratosis follicularis, also known as Darier disease, is a rare, genetic skin disorder. Affected individuals develop skin lesions that consist of thickened, rough bumps (papules) or plaques that may also be greasy or have a brown or yellow crust. ...

Meleda disease is an extremely rare inherited skin disorder characterized by the slowly progressive development of dry, thick patches of skin on the palms of the hands and soles of the feet (palmoplantar hyperkeratosis). Affected skin may be unusu...

Haim-Munk syndrome is a rare genetic disorder characterized by the development of red, scaly thickened patches of skin on the palms of the hands and soles of the feet (palmoplantar hyperkeratosis), frequent pus-producing (pyogenic) skin infections...

Bilateral Renal Agenesis is the absence of both kidneys at birth. It is a genetic disorder characterized by a failure of the kidneys to develop in a fetus. This absence of kidneys causes a deficiency of amniotic fluid (Oligohydramnios) in a pregna...

The Course of Kidney Disease Diabetic kidney disease takes many years to develop. In some people, the filtering function of the kidneys is actually higher than normal in the first few years of their diabetes. Over several years, pe...

Kikuchi's disease, also known as histiocytic necrotizing lymphadenopathy, is a rare, benign, (noncancerous, nonmalignant) disorder of the lymph nodes of young adults, predominantly in young women. This disorder is often mistaken for malignant lymp...

Kohler disease is a rare bone disorder of the foot in children that may be the result of stress-related compression at a critical time during the period of growth. It is characterized by limping caused by pain and swelling in the foot. It most oft...

Degos disease is an extremely rare disorder in which small and medium sized arteries become blocked (occlusive arteriopathy), restricting the flow of blood to affected areas. Degos disease usually causes characteristic skin lesions that may last f...

Kyphosis facts There are three main types of kyphosis: postural, Scheuermann's, and congenital. Most cases of kyphosis do not require any treatment. Physical therapy and exercise are often effective in postural a...

Lactose intolerance is the inability to digest and absorb lactose (the sugar in milk) that results in gastrointestinal symptoms when milk or food products containing milk are consumed.        ...

Madelung's disease is a disorder of fat metabolism (lipid storage) that results in an unusual accumulation of fat deposits around the neck and shoulder areas. Adult alcoholic males are most often affected, although women and those who do not drink...

Very long-chain acyl-CoA dehydrogenase deficiency (VLCAD) is a rare genetic disorder of fatty acid metabolism that is transmitted as an autosomal recessive trait. It occurs when an enzyme needed to break down certain very long-chain fatty acids is...

Legg-Calvé-Perthes Disease (LCPD) is one of a group of disorders known as the Osteochondroses. The Osteochondroses typically are characterized by degeneration (avascular necrosis) and subsequent regeneration of the growing end of a bone (ep...

Granuloma annulare is a chronic degenerative skin disorder. The most common form is localized granuloma annulare, which is characterized by the presence of small, firm red or yellow colored bumps (nodules or papules) that appear arranged in a ring...

Lichen planus facts Lichen planus is a chronic recurrent rash of unknown cause with no established cure. Lichen planus generally affects adults and can involve any portion of the body, but it has a predilection for the wri...

Lichen planus is a chronic inflammatory condition that affects the skin, mucous membranes, hair, and nails. It is characterized by the presence of itchy, flat-topped, purple or reddish bumps that may be covered with white scales. The exact cause o...

Lichen Planus is a rare, recurrent, itchy rash or area of inflammatory eruptions (lesions) of unknown origin characterized by shiny reddish-purple spots on the skin and gray-white ones in the mouth. The disorder may present as itchy spots on the w...

Von Hippel-Lindau syndrome (VHL) is an autosomal dominant genetic disorder characterized by the abnormal growth of blood vessels in certain parts of the body (angiomatosis). Very small blood vessels (capillaries) "knot" together to form benign gro...

Chanarin Dorfman syndrome is a rare hereditary disorder of fat (lipid) metabolism. It is characterized by scaly skin (ichthyosis), degeneration of the muscles (myopathy), and abnormal white blood cells with small spaces (vacuoles) filled with fat ...

Familial lipoprotein lipase (LPL) deficiency is a rare genetic metabolic disorder characterized by a deficiency of the enzyme lipoprotein lipase. The deficiency of this enzyme prevents affected individuals from properly digesting certain fats and ...

Listeriosis is a serious infection usually caused by eating food contaminated with the bacterium Listeria monocytogenes. It primarily affects pregnant women, newborns, the elderly, and individuals with weakened immune systems. Symptoms may include...

Listeriosis is an infection caused by a gram-positive motile bacterium named Listeria monocytogenes. The infection produces fever, muscle aches, and, in many people, diarrhea. Severe infections can cause headaches, meningitis, convulsions, and dea...

Sneddon syndrome is a rare progressive disorder affecting the blood vessels characterized by the association of a skin condition and neurological abnormalities. Characteristics include multiple episodes of reduced blood flow to the brain (cerebral...

Drug-induced liver diseases are diseases of the liver that are caused by physician-prescribed medications, over-the-counter medications, vitamins, hormones, herbs, illicit ("recreational") drugs, and environmental toxins. What is the liver...

Osteogenesis Imperfecta (OI) is a group of rare disorders affecting the connective tissue and characterized by extremely fragile bones that break or fracture easily (brittle bones), often without apparent cause. The specific symptoms and physical ...

Epidermolysis bullosa (EB) is a genetic skin disorder characterized clinically by blister formation from mechanical trauma. There are four main types with additional sub-types identified. There is a spectrum of severity, and within each type, one ...

Urticaria pigmentosa is a rare skin disorder that is a localized (cutaneous) form of mastocytosis. Some clinicians suggest that urticaria pigmentosa is the childhood form of mastocytosis. Mast cells are specialized cells of connective tissue that ...

Ataxia telangiectasia (AT) is a complex genetic neurodegenerative disorder that may become apparent during infancy or early childhood. The disorder is characterized by progressively impaired coordination of voluntary movements (ataxia), the develo...

Familial lipoprotein lipase (LPL) deficiency is a rare genetic metabolic disorder characterized by a deficiency of the enzyme lipoprotein lipase. Deficiency of this enzyme prevents affected individuals from properly digesting certain fats and resu...

Lymphangioleiomyomatosis (LAM) is a condition that occurs due to abnormal growth of smooth muscle cells, especially in the lymphatic systems and the lungs. This growth leads to the formation of cysts or holes in the lungs.  Peo...

Macular degeneration facts The macula is in the center of the retina, the light-sensitive layer of tissue at the back of the eye. The macula is responsible for central vision (straight-ahead vision). Degeneration of the macula occur...

Noonan syndrome is a common genetic disorder that is typically evident at birth (congenital). The disorder is characterized by a wide spectrum of symptoms and physical features that vary greatly in range and severity. In many affected individuals,...

Degos disease is an extremely rare disorder in which small and medium sized arteries become blocked (occlusive arteriopathy), restricting the flow of blood to affected areas. Degos disease usually causes characteristic skin lesions that may last f...

Pseudomyxoma peritonei is a rare malignant growth characterized by the progressive accumulation of mucus-secreting (mucinous) tumor cells within the abdomen and pelvis. The disorder develops after a small growth (polyp) located within the appendix...

Pseudomyxoma peritonei is a rare malignant growth characterized by the progressive accumulation of mucus-secreting (mucinous) tumor cells within the abdomen and pelvis. The disorder develops after a small growth (polyp) located within the appendix...

Pseudomyxoma peritonei is a rare malignant growth characterized by the progressive accumulation of mucus-secreting (mucinous) tumor cells within the abdomen and pelvis. The disorder develops after a small growth (polyp) located within the appendix...

Pseudomyxoma peritonei is a rare malignant growth characterized by the progressive accumulation of mucus-secreting (mucinous) tumor cells within the abdomen and pelvis. The disorder develops after a small growth (polyp) located within the appendix...

Mallory-Weiss syndrome refers to a tear or laceration of the mucous membrane, most commonly at the point where the esophagus and the stomach meet (gastroesophageal junction). Such a tear may result in severe bleeding from the gastrointestinal trac...

Mallory-Weiss syndrome refers to a tear or laceration of the mucous membrane, most commonly at the point where the esophagus and the stomach meet (gastroesophageal junction). Such a tear may result in severe bleeding from the gastrointestinal trac...

Marinesco-Sjogren syndrome (MSS) is a rare genetic disorder that affects multiple organ systems of the body. Common symptoms include difficulty coordinating voluntary movements due to degeneration (atrophy) of the cerebellum (cerebellar ataxia), c...

Marinesco-Sjogren syndrome (MSS) is a rare genetic disorder that affects multiple organ systems of the body. Common symptoms include difficulty coordinating voluntary movements due to degeneration (atrophy) of the cerebellum (cerebellar ataxia), c...

Encephalitis is an inflammation of the brain. Meningitis is an inflammation of the membranes (called meninges) that surround the brain and spinal cord. Both infections can be caused by bacteria or viruses and rarely a fung...

Meningococcal disease is a serious bacterial infection caused by the bacterium Neisseria meningitidis. It can lead to meningitis (inflammation of the membranes surrounding the brain and spinal cord) and septicemia (blood poisoning). Meningococcal ...

Menopause is defined as the absence of menstrual periods for 12 months. It is the time in a woman's life when the function of the ovaries ceases. The process of menopause does not occur overnight, but rather is a gradual process. Th...

Menopause is defined as the absence of menstrual periods for 12 months. It is the time in a woman's life when the function of the ovaries ceases. The process of menopause does not occur overnight, but rather is a gradual process. Th...

Menstrual cramps that occur in the absence of a known abnormality or cause are medically referred to as primary dysmenorrhea. Non-drug treatments for menstrual cramps include adequate rest and sleep, regular exercise (especially wal...

The methylmalonic acidemias are organic acidemias caused by an enzymatic defect in the metabolism of four amino acids (methionine, threonine, isoleucine and valine). This results in an abnormally high level of acid in the blood (academia) and body...

Microcephaly is a condition where the head (circumference) is smaller than normal. Microcephaly may be caused by genetic abnormalities or by drugs, alcohol, certain viruses, and toxins that are exposed to the fetus during pregnancy ...

Collagenous colitis is a rare digestive disorder that primarily affects females and typically becomes apparent during middle age. The disorder is characterized by inflammatory changes of the mucous membranes (mucosa) of the colon (colitis) and abn...

Microvillus inclusion disease is an extremely rare inherited intestinal disorder (enteropathy) that is typically apparent within hours or days after birth. The disorder is characterized by chronic, severe, watery diarrhea and insufficient absorpti...

Migraine headache is a result of specific changes within the brain. It causes severe head pain that is often accompanied by sensitivity to light, sound, or smells. Common symptoms of migraine are: Eye pain Sensi...

Moebius syndrome is a rare neurological disorder characterized by weakness or paralysis (palsy) of multiple cranial nerves, most often the 6th (abducens) and 7th (facial) nerves. Other cranial nerves are sometimes affected. The disorder is present...

Peripheral neuropathy is an umbrella term that denotes a disorder of, or damage to, the peripheral nervous system. The peripheral nervous system consists of all the motor and sensory nerves that connect the brain and spinal cord to the rest of the...

Chromosome 18, Monosomy 18p is a rare chromosomal disorder in which all or part of the short arm (p) of chromosome 18 is deleted (monosomic). The disorder is typically characterized by short stature, variable degrees of mental retardation, speech ...

Chromosome 3, Monosomy 3p is a rare chromosomal disorder in which the end (distal) portion of the short arm (p) of chromosome 3 is missing (deleted or monosomic). The range and severity of symptoms and findings may be variable. However, associated...

Marinesco-Sjogren syndrome (MSS) is a rare genetic disorder that affects multiple organ systems of the body. Common symptoms include difficulty coordinating voluntary movements due to degeneration (atrophy) of the cerebellum (cerebellar ataxia), c...

Hyperostosis Frontalis Interna is characterized by the thickening of the frontal bone of the skull. It is not clear that this disorder is actually rare. Some clinicians believe that it may be a common abnormality found in as many as 12 percent of ...

Morquio syndrome (mucopolysaccharidosis type IV; MPS IV) is a mucopolysaccharide storage disease that exists in two forms (Morquio syndromes A and B) and occurs because of a deficiency of the enzymes N-acetyl-galactosamine-6-sulfatase and beta-gal...

Syringomyelia is a neurological disorder characterized by the formation of a fluid-filled cyst (syrinx) within the spinal cord. This cyst may, for unknown reasons, expand during adolescence or the young adult years, destroying the center of the sp...

Mucopolysaccharidoses, which are also known as mucopolysaccharide storage (MPS) diseases, are a group of rare genetic disorders caused by the deficiency of one of ten specific lysosomal enzymes. The lysosomes are particles bound in membranes withi...

Maroteaux-Lamy syndrome is a rare genetic metabolic disorder that belongs to a group of disorders known the mucopolysaccharidoses. The disorder is also known as mucopolysaccharidosis (MPS) type VI. Maroteaux-Lamy syndrome occurs in three types: a ...

Pseudomyxoma peritonei is a rare malignant growth characterized by the progressive accumulation of mucus-secreting (mucinous) tumor cells within the abdomen and pelvis. The disorder develops after a small growth (polyp) located within the appendix...

I-cell disease (mucolipidosis II) is a rare inherited metabolic disorder characterized by coarse facial features, skeletal abnormalities and mental retardation. The symptoms of I-cell disease are similar to but more severe than those of Hurler syn...

General DiscussionPseudo-Hurler polydystrophy (mucolipidosis type III) is a rare genetic metabolic disorder characterized by a defective enzyme known as UPD-N-acetylglucosamine-1-phosphotransferase. This defective enzyme ultimately result...

Mayer-Rokitansky-Kuster-Hauser (MRKH) syndrome is a rare disorder that affects women. It is characterized by the failure of the uterus and the vagina to develop properly in women who have normal ovarian function and normal external genitalia. Wome...

Mayer-Rokitansky-Kuster-Hauser (MRKH) syndrome is a rare disorder that affects women. It is characterized by the failure of the uterus and the vagina to develop properly in women who have normal ovarian function and normal external genitalia. Wome...

Multiple epiphyseal dysplasia (MED) is a rare inherited spectrum of disorders characterized by malformation (dysplasia) of the "growing portion" or head of the long bones (epiphyses). Affected individuals may have an abnormally short thighbone (fe...

Familial adenomatous polyposis (FAP) is a rare inherited cancer predisposition syndrome characterized by hundreds to thousands of precancerous colorectal polyps (adenomatous polyps). If left untreated, affected individuals inevitably develop cance...

Familial adenomatous polyposis (FAP) is a rare inherited cancer predisposition syndrome characterized by hundreds to thousands of precancerous colorectal polyps (adenomatous polyps). If left untreated, affected individuals inevitably develop cance...

Munchausen syndrome is a mental disorder that is characterized by the sufferer causing or pretending to have physical or psychological symptoms in his or herself. Adults aged 20-40 years are the most likely groups to develop Munchau...

Nager Syndrome is a rare disorder that may or may not be genetically derived. Major symptoms may include underdevelopment of the cheek and jaw area of the face. Down-sloping of the opening of the eyes, a smaller than normal jaw, lack or absence of...

Nail-patella syndrome (NPS) is a rare genetic disorder that is usually apparent at birth or during early childhood. Although the symptoms and physical characteristics associated with NPS may vary, characteristic abnormalities tend to include impro...

Narcolepsy is a chronic disease of the central nervous system. The symptoms include excessive daytime sleepiness (EDS), loss of muscle tone (cataplexy), distorted perceptions (hypnagogic hallucinations), inability to move or talk (sleep paralysis)...

Binder type maxillonasal dysplasia is a rare condition characterized by abnormal development (dysplasia) of the nasal and upper jaw (nasomaxillary) regions. Affected individuals typically have an unusually flat, underdeveloped midface (midfacial h...

Nasopharyngeal cancer is a disease in which malignant (cancer) cells form in the tissues of the nasopharynx. The nasopharynx is the upper part of the pharynx (throat) behind the nose. The pharynx is a hollow tube about 5 inches long that s...

Nasopharyngeal cancer is a disease in which malignant (cancer) cells form in the tissues of the nasopharynx. The nasopharynx is the upper part of the pharynx (throat) behind the nose. The pharynx is a hollow tube about 5 inches long that s...

Cockayne Syndrome (CS) is a rare form of dwarfism. It is an inherited disorder whose diagnosis depends on the presence of three signs (1) growth retardation, i.e. short stature, (2) abnormal sensitivity to light (photosensitivity), and (3) prematu...

Listeriosis is a rare but serious infectious disease caused by the bacterium Listeria monocytogenes, which is predominantly transmitted to humans through the consumption of contaminated food. Clinical syndromes associated with listeriosis include ...

Alport syndrome is a group of hereditary disorders characterized by progressive deterioration of parts of the kidney known as basement membranes. This deterioration may lead to chronic kidney (renal) disease. Eventually, severe renal failure (end-...

Diabetic Retinopathy is a complication of diabetes and a disorder of the light sensitive tissue of the eye (the retina). This condition is characterized by destructive changes in the blood vessels of the retina, which, if left unchecked, may lead ...

Epidermolysis bullosa (EB) is a genetic skin disorder characterized clinically by blister formation from mechanical trauma. There are four main types with additional sub-types identified. There is a spectrum of severity, and within each type, one ...

Renal glycosuria, also known as renal glucosuria, is a rare condition in which the simple sugar glucose is eliminated (excreted) in the urine despite normal or low blood glucose levels. With normal kidney (renal) function, glucose is excreted in t...

Henoch-Schonlein purpura is a rare inflammatory disease of the small blood vessels (capillaries) and is usually a self-limited disease. It is the most common form of childhood vascular inflammation (vasculitis) and results in inflammatory changes ...

Norovirus is a highly contagious virus that causes gastroenteritis, which is inflammation of the stomach and intestines. It is commonly referred to as the "stomach flu" or "winter vomiting bug" because it often causes symptoms such as vomiting, di...

A norovirus is a small virus that contains RNA and is surrounded by a protein coating. By sequencing the RNA, scientists have discovered that there are many different types of norovirus. Originally, strains were named based on the city in which th...

Oculo-dento-digital dysplasia is a rare disorder that may be inherited as an autosomal dominant trait or be caused by a new change in the genes that occurs for no apparent reason (mutation). There also have been a few instances in which it is thou...

Nail-patella syndrome (NPS) is a rare genetic disorder that is usually apparent at birth or during early childhood. Although the symptoms and physical characteristics associated with NPS may vary, characteristic abnormalities tend to include impro...

Stickler syndrome refers to a group of disorders of connective tissue. Connective tissue, which is distributed throughout the body, multiple organ systems can be affected. The specific symptoms present in Stickler syndrome often vary greatly from ...

Neuromyelitis optica, also known as Devic disease (DD), is a chronic disorder of nerve tissue characterized by inflammation of the optic nerve (optic neuritis) and inflammation of the spinal cord (myelitis). There appear to be two forms of this di...

General DiscussionRetroperitoneal fibrosis is a rare inflammatory disorder in which abnormal formation of fiber-like tissue (fibrosis) occurs behind the membrane that lines the cavity of the abdomen (peritoneum). This abnormal tissue grow...

Osteoarthritis facts Osteoarthritis is a joint inflammation that results from cartilage degeneration. Osteoarthritis can be caused by aging, heredity, and injury from trauma or disease. The most common symptom of...

Osteoarthritis facts Osteoarthritis is a joint inflammation that results from cartilage degeneration. Osteoarthritis can be caused by aging, heredity, and injury from trauma or disease. The most common symptom of...

Ovarian cancer is a type of cancer that begins in the ovaries. The female reproductive system contains two ovaries, one on each side of the uterus. The ovaries — each about the size of an almond — produce eggs (ova) as well as the horm...

The term "ovarian cancer" includes several different types of cancer that all arise from cells of the ovary. Most commonly, tumors arise from the epithelium, or lining cells, of the ovary. These include epithelial ovarian (from the cells on the su...

Overactive bladder (OAB) facts Overactive bladder is an involuntary and sudden contraction of the muscle in the wall of the urinary bladder. Overactive bladder can also result in urinary incontinence, otherwise termed urge...

Hyperoxaluria occurs when you have too much oxalate in your urine. Oxalate is a natural chemical in your body, and it's also found in certain types of food. But too much oxalate in your urine can cause serious problems. Hyperoxaluria can b...

Idiopathic nodular panniculitis is a rare spectrum of skin disorders characterized by single or multiple, tender or painful bumps below the surface of the skin (subcutaneous nodules) that usually lead to inflammation of the subcutaneous layer of f...

Idiopathic nodular panniculitis is a rare spectrum of skin disorders characterized by single or multiple, tender or painful bumps below the surface of the skin (subcutaneous nodules) that usually lead to inflammation of the subcutaneous layer of f...

Progressive supranuclear palsy, or PSP, is a rare neurodegenerative disease that is often misdiagnosed as Parkinson's disease because it carries similar symptoms. Because of its rarity, PSP is mostly unknown by the general public....

Pelvic Inflammatory Disease (PID) is an infection of the female reproductive organs, including the uterus, fallopian tubes, and ovaries. It is usually caused by sexually transmitted infections such as chlamydia and gonorrhea, but can also be cause...

What is a peptic ulcer? A peptic ulcer is a break in the inner lining of the esophagus, stomach, or duodenum. A peptic ulcer of the stomach is called a gastric ulcer; of the duodenum, a duodenal ulcer; and of the esophagus, an esophageal u...

Peritonitis is inflammation of the peritoneum — a silk-like membrane that lines your inner abdominal wall and covers the organs within your abdomen — that is usually due to a bacterial or fungal infection. Peritonitis can result from a...

Cholinergic urticaria is a relatively common disorder of the immune system characterized by an immediate skin reaction (hypersensitivity) to heat, emotional stress, and/or exercise. Symptoms of the disorder include the appearance of distinctive sm...

Cholinergic urticaria is a relatively common disorder of the immune system characterized by an immediate skin reaction (hypersensitivity) to heat, emotional stress, and/or exercise. Symptoms of the disorder include the appearance of distinctive sm...

Refsum disease is one of a family of genetic disorders known as the leukodystrophies in which, as a consequence of the disruption of lipid metabolism, the myelin sheath that insulates and protects the nerves of the brain fails to grow. It is inher...

Refsum disease is one of a family of genetic disorders known as the leukodystrophies in which, as a consequence of the disruption of lipid metabolism, the myelin sheath that insulates and protects the nerves of the brain fails to grow. It is inher...

Frontotemporal dementia (FTD), or Pick's disease, is a syndrome featuring shrinking of the frontal and temporal anterior lobes of the brain. The symptoms of frontotemporal dementia fall into two clinical patterns that involve either...

Pineal cysts are benign (non-cancerous) fluid-filled sacs located in the region of the brain that contains the pineal gland. Small pineal cysts (.5 cm or smaller) are common occurrences, often found incidentally on routine neurological exams. Smal...

Pinworms facts Pinworm infections are caused by worm-like parasites that infect humans' intestines and rectal/anal areas. Young children and their household members are at risk for pinworm infections. Pinworms ar...

Placenta previa is the attachment of the placenta to the wall of the uterus in a location that completely or partially covers the uterine outlet (opening of the cervix). Bleeding after the 20th week of gestation is the main symptom ...

The liver serves many purposes within the body from making carbohydrates, proteins and fats to synthesizing bile to help digest found. Because of this, the liver requires a significant blood supply. As opposed to other organs in the body, the majo...

Posttraumatic stress disorder (PTSD) is an emotional illness that was first formally diagnosed in soldiers and war veterans and is usually caused by terribly frightening, life-threatening, or otherwise highly unsafe experiences but can also be cau...

Preeclampsia is a pregnancy complication characterized by high blood pressure and signs of damage to another organ system, most often the liver and kidneys. Preeclampsia usually begins after 20 weeks of pregnancy in women whose blood pressure had ...

General DiscussionWolff-Parkinson-White (WPW) syndrome is a rare congenital heart disorder involving irregularities in the electrical system of the heart. In individuals with WPW syndrome, an abnormal alternate electrical pathway (accesso...

Premature ovarian failure — also known as primary ovarian insufficiency — is a loss of normal function of your ovaries before age 40. If your ovaries fail, they don't produce normal amounts of the hormone estrogen or release eggs regul...

Premenstrual dysphoric disorder (PMDD) can be considered to be a severe form of premenstrual syndrome (PMS), with symptoms that interfere with daily activities and functioning. PMDD occurs in 3% to 8% of menstruating women. ...

Problem sleepiness occurs when sleepiness during the day interferes with work or social functioning. Symptoms of problem sleepiness may include difficulty concentrating, falling asleep while driving, or problems with emotional contr...

A pituitary tumor is a tumor that forms in the pituitary gland near the brain that can cause changes in hormone levels in the body. This illustration shows a smaller tumor (microadenoma). Pituitary tumors are abnormal growths that develop ...

Prostate cancer is cancer that occurs in the prostate. The prostate is a small w...

Prostate cancer is cancer that occurs in the prostate. The prostate is a small w...

screening for prostate cancer Testing healthy men with no symptoms for p...

screening for prostate cancer Testing healthy men with no symptoms for p...

Pseudotumor cerebri literally means "false brain tumor." It is likely due to high pressure within the skull caused by the buildup or poor absorption of cerebrospinal fluid (CSF). The disorder is most common in women between the ages of 20 and 50....

Psoriatic arthritis facts Psoriatic arthritis is a chronic disease characterized by a form of inflammation of the skin (psoriasis) and joints (inflammatory arthritis). Some 10%-15% of people with psoriasis also develop inf...

Psoriatic arthritis is a chronic disease characterized by a form of inflammation of the skin (psoriasis) and joints (inflammatory arthritis). Some 10%-15% of people with psoriasis also develop inflammation of joints (psoriatic arthr...

Psychotic disorders include schizophrenia and a number of lesser-known disorders. The number of people who develop a psychotic disorder tends to vary depending on the country, age, and gender of the sufferer, as well as on the speci...

Pump lung, (also known as Shock Lung), is inflammatory lung damage.  Pump lung is caused by fluid buildup in the lungs' small air sacs (called alveoli), which makes breathing very difficult. It also results in severely low bloo...

Radiation sickness describes the harmful effects--acute, delayed, or chronic--produced by exposure to ionizing radiation. An observable effect due to radiation exposure becomes quite certain after a single dose of several hundred rads. As a rule, ...

Radiation sickness describes the harmful effects--acute, delayed, or chronic--produced by exposure to ionizing radiation. An observable effect due to radiation exposure becomes quite certain after a single dose of several hundred rads. As a rule, ...

Radiation sickness is damage to your body caused by a large dose of radiation often received over a short period of time (acute). The amount of radiation absorbed by the body — the absorbed dose — determines how sick you'll be. ...

Radiation sickness describes the harmful effects--acute, delayed, or chronic--produced by exposure to ionizing radiation. An observable effect due to radiation exposure becomes quite certain after a single dose of several hundred rads. As a rule, ...

Rapp-Hodgkin syndrome, an extremely rare inherited multisystem disorder that is apparent at birth (congenital) or during infancy, belongs to a group of diseases known as ectodermal dysplasias. Ectodermal dysplasias typically affect the skin, teeth...

Retinitis pigmentosa is the most common of a group of hereditary progressive retinal degenerations or dystrophies. There is considerable variation and overlap among the various forms of retinitis pigmentosa. Common to all of them is progressive de...

Sydenham chorea is a rare neurological disorder characterized by rapid, involuntary, purposeless movements, especially of the face, feet and hands. Additional symptoms may include muscle weakness and emotional or behavioral problems. Sydenham chor...

Familial dysautonomia is a rare genetic disorder of the autonomic nervous system (ANS) that primarily affects people of Eastern European Jewish heritage. It is characterized by diminished sensitivity to pain, lack of overflow tearing in the eyes, ...

Budd-Chiari syndrome is a rare disorder characterized by narrowing and obstruction (occlusion) of the veins of the liver (hepatic veins). Symptoms associated with Budd Chiari syndrome include pain in the upper right part of the abdomen, an abnorma...

General DiscussionRomano-Ward syndrome is an inherited heart (cardiac) disorder characterized by abnormalities affecting the electrical system of the heart. The severity of Romano-Ward syndrome varies greatly from case to case. Some indiv...

Roseola facts Roseola is a mild illness caused by a virus infection most commonly involving, young children. A sudden high fever that lasts for three to five days is an early feature of roseola. Mild nasal congestion and l...

Rotavirus is a highly contagious virus that causes inflammation of the stomach and intestines, leading to symptoms such as severe diarrhea, vomiting, fever, and abdominal pain. It is a common cause of gastroenteritis in infants and young children,...

Rothmund-Thomson syndrome (RTS) is a rare genetic disorder that can affect many parts of the body. The disorder is characterized by distinctive abnormalities of the skin, sparse hair, eyelashes and/or eyebrows, small stature, skeletal and dental a...

Russell-Silver syndrome (RSS) is a rare disorder characterized by intrauterine growth retardation and postnatal growth deficiency along with a handful of common physical characteristics and a range of other symptoms. The wide spectrum of phenotype...

Japanese Encephalitis is a severe inflammation of the brain caused by the Japanese B Encephalitis Virus that is transmitted by the bite of infected mosquitoes in certain areas of the world, particularly Asia. This disorder most commonly affects ch...

Salmonellosis is a type of food poisoning caused by the Salmonella bacteria. It is typically contracted by consuming contaminated food or water. Symptoms of salmonellosis include diarrhea, fever, abdominal cramps, and vomiting. In most cases, the ...

Sandhoff disease is a lipid storage disorder characterized by a progressive deterioration of the central nervous system. The clinical symptoms of Sandhoff disease are identical to Tay-Sachs disease. Sandhoff disease is an autosomal recessive genet...

Schizoaffective disorder is an illness characterized by psychotic symptoms (delusions and hallucinations) and mood problems. There are two types of schizoaffective disorder: bipolar and depressive. There is no specific kno...

Schizophrenia is a chronic, severe, debilitating mental illness that affects about 1% of the population, more than 2 million people in the United States alone. With the sudden onset of severe psychotic symptoms, the individual is sa...

Scleroderma facts Scleroderma is a disease of the connective tissue featuring skin thickening that can involve scarring, blood vessel problems, varying degrees of inflammation, and is associated with an overactive immune system....

Shigellosis is an infectious disease caused by a group of bacteria called Shigella. It is typically spread through contaminated food or water, or through close contact with an infected person. Symptoms of shigellosis can include diarrhea, fever, s...

Sick building syndrome is believed by some to be an illness caused by unknown agents in buildings. Sick building syndrome is a controversial subject because many experts do not think it is a true syndrome. Sick building sy...

Weismann-Netter-Stuhl syndrome is an extremely rare genetic skeletal disorder characterized by the abnormal development of bone (osseousbo dysplasia). Affected individuals exhibit bowing of the long portions (shafts) of the shinbone (tibia) and th...

Dyggve-Melchior-Clausen (DMC) syndrome is a rare, progressive genetic disorder characterized by abnormal skeletal development, microcephaly and intellectual disability. The condition was first reported by Dyggve, Melchior and Clausen in 1962 in th...

Batten disease, a rare genetic disorder, belongs to a group of progressive degenerative neurometabolic disorders known as the neuronal ceroid lipofuscinoses. These disorders share certain similar symptoms and are distinguished in part by the age a...

Batten disease, a rare genetic disorder, belongs to a group of progressive degenerative neurometabolic disorders known as the neuronal ceroid lipofuscinoses. These disorders share certain similar symptoms and are distinguished in part by the age a...

Friedreich's Ataxia is a genetic, progressive, neurologic movement disorder that typically becomes apparent before adolescence. Initial symptoms may include unsteady posture, frequent falling, and progressive difficulties walking due to an impaire...

Spinal headaches are a fairly common complication in those who undergo a spinal tap (lumbar puncture) or spinal anesthesia. Both procedures require a puncture of the membrane that surrounds the spinal cord and, in the lower spine, the lumbar and s...

The hereditary ataxias are a group of neurological disorders (ataxias) of varying degrees of rarity that are inherited, in contrast to a related group of neurological disorders that are acquired through accidents, injuries, or other external agent...

Split hand/split foot malformation (SHFM) is a genetic disorder characterized by the complete or partial absence of some fingers or toes, often combined with clefts in the hands or feet. There may also be the appearance of webbing between fingers ...

Split hand/split foot malformation (SHFM) is a genetic disorder characterized by the complete or partial absence of some fingers or toes, often combined with clefts in the hands or feet. There may also be the appearance of webbing between fingers ...

Subacute cerebellar degeneration (SCD) is characterized by the deterioration of the area of the brain concerned with muscle coordination and balance (the cerebellum). Less frequently, the area involved may include the area connecting the spinal co...

Creutzfeldt-Jakob disease (CJD) is an extremely rare degenerative brain disorder (i.e., spongiform encephalopathy) characterized by sudden development of rapidly progressive neurological and neuromuscular symptoms. With symptom onset, affected ind...

Metachromatic leukodystrophy, the most common form of leukodystrophy, is a rare inherited neurometabolic disorder affecting the white matter of the brain (leukoencephalopathy). It is characterized by the accumulation of a fatty substance known as ...

Introduction The superior vena cava is a large vein located in the upper chest, which collects blood from the head and arms and delivers it back to the right atrium of the heart. If this vein is compressed by outside structures, or if a th...

Syphilis is a sexually transmitted disease (STD) caused by an infection with bacteria known as Treponema pallidum. Like other STDs, syphilis can be spread by any type of sexual contact. Syphilis can also be spread from an infected mother to the fe...

Congenital syphilis is a chronic infectious disease caused by a spirochete (treponema pallidum) acquired by the fetus in the uterus before birth. Symptoms of this disease may not become apparent until several weeks or months after birth and, in so...

Pseudoxanthoma elasticum, PXE, is an inherited disorder caused y mutations in the ABCC6 transporter gene that affects connective tissue in some parts of the body. Elastic tissue in the body becomes mineralized; that is, calcium and other minerals ...

Systemic mastocytosis (mas-to-sy-TOE-sis) is a disorder that results in an excessive number of mast cells in your body. Mast cells normally help protect you from disease and aid in wound healing by releasing substances such as histamine and leukot...

Scleroderma is a rare autoimmune connective tissue disorder characterized by abnormal thickening of the skin. Connective tissue is composed of collagen, which supports and binds other body tissues. There are several types of scleroderma. Some type...

Tricho-dento-osseous (TDO) syndrome is an autosomal dominant genetic disorder that belongs to a group of diseases known as ectodermal dysplasias. Ectodermal dysplasias typically affect the hair, teeth, nails, and/or skin. TDO syndrome is character...

Thoracic outlet syndrome is a condition whereby symptoms are produced from compression of nerves or blood vessels, or both, because of an inadequate passageway through an area (thoracic outlet) between the base of the neck and the armpit. ...

Pentalogy of Cantrell is a rare disorder that is present at birth (congenital). Pentalogy of Cantrell is characterized by a combination of birth defects. These birth defects can potentially involve the breastbone (sternum), the muscle that separat...

Pentalogy of Cantrell is a rare disorder that is present at birth (congenital). Pentalogy of Cantrell is characterized by a combination of birth defects. These birth defects can potentially involve the breastbone (sternum), the muscle that separat...

Three M syndrome is an extremely rare genetic disorder characterized by low birth weight, short stature (dwarfism), characteristic abnormalities of the head and facial (craniofacial) area, distinctive skeletal malformations, and/or other physical ...

What are yeast infections? What are commonly known as "yeast" infections are caused by various species of a yeast-like fungus called Candida, particularly the species Candida albicans. Yeast organisms are part of the germs (including bacte...

Cryptococcosis is caused by a fungus known as Cryptococcosis neoformans. The infection may be spread to humans through contact with pigeon droppings or unwashed raw fruit. Contact with an infected individual may also spread the infection. Individu...