1p36 deletion syndrome facts Introduction to the 1p36 deletion syndrome – how individuals get chromosomes with missing DNA 1p36 deletion syndrome stands for the following: 1 is the chromosome number that has deleted ...

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 aortic aneurysm facts 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 ...

Abdominal aortic aneurysm facts 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 ...

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...

Abdominal pain facts Abdominal pain is pain that is felt in the part of the trunk below the ribs and above the pelvis. Abdominal pain comes from organs within the abdomen or organs adjacent to the abdomen. Abdomi...

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...

Adams-Oliver syndrome (AOS) is an extremely rare inherited disorder characterized by defects of the scalp and abnormalities of the fingers, toes, arms, and/or legs. The physical abnormalities associated with this disorder vary greatly among affect...

Neuroacanthocytosis is a general term for a group of rare progressive disorders characterized by the association of misshapen, spiny red blood cells (acanthocytosis) and neurological abnormalities, especially movement disorders. Chorea, which is c...

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 ...

Acanthosis nigricans is a skin condition characterized by areas of dark, velvety discoloration in body folds and creases. The affected skin can become thickened. Most often, acanthosis nigricans affects your armpits, groin and neck. The sk...

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...

Fetal retinoid syndrome is a characteristic pattern of mental and physical birth defects that results from maternal use of retinoids, the synthetic derivatives of vitamin A, during pregnancy. The most well known retinoid is isotretinoin (Accutane)...

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...

Achalasia is a rare disease of the muscle of the esophagus (swallowing tube). The term achalasia means "failure to relax" and refers to the inability of the lower esophageal sphincter (a ring of muscle situated between the lower esophagus and the ...

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....

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...

Gaucher disease is a rare, inherited metabolic disorder in which deficiency of the enzyme glucocerebrosidase results in the accumulation of harmful quantities of certain fats (lipids), specifically the glycolipid glucocerebroside, throughout the b...

Pompe disease is a rare multisystem genetic disorder that is characterized by absence or deficiency of the lysosomal enzyme alpha-glucosidase (GAA). This enzyme is required to breakdown (metabolize) the complex carbohydrate glycogen and convert it...

A rare genetic condition where the body can't process proteins adequately. More specifically, there are insufficient levels of the enzyme needed to break down an amino acid called leucine. This results in a build up of isovaleric acid which can harm ...

Acne is a skin condition that occurs when your hair follicles become plugged with oil and dead skin cells. It often causes whiteheads, blackheads or pimples, and usually appears on the face, forehead, chest, upper back and shoulders. Acne is most ...

Acne (acne vulgaris, common acne) is a disease of the hair follicles of the face, chest, and back that affects almost all teenagers during puberty -- the only exception being members of a few primitive Neolithic tribes living in isolatio...

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...

An actinic keratosis (ak-TIN-ik ker-uh-TOE-sis) is a rough, scaly patch on your skin that develops from years of exposure to the sun. It's most commonly found on your face, lips, ears, back of your hands, forearms, scalp or neck. Also know...

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 ...

Salivary gland type malignant neoplasm arising from bronchial seromucinous glands. Composed of epithelial and myoepithelial cells in cribriform, tubular and solid growth patterns....

Adie's pupil is a type of pupil abnormality that is characterized by a sluggish or absent pupillary response to light. It is named after the Scottish neurologist William John Adie, who first described the condition in 1931. The condition is caused...

Understanding the key reason of adult-onset asthma and identifying unique phenotypes may hel...

Agenesis of corpus callosum (ACC) is a rare disorder that is present at birth (congenital). It is characterized by a partial or complete absence (agenesis) of an area of the brain that connects the two cerebral hemispheres. This part of the brain ...

Agoraphobia is a fear of being outside or otherwise being in a situation from which one either cannot escape or from which escaping would be difficult or humiliating. Like other phobias, agoraphobia often goes unreported, probably b...

Acquired agranulocytosis is a rare, drug-induced blood disorder that is characterized by a severe reduction in the number of white blood cells (granulocytes) in the circulating blood. The name granulocyte refers to grain-like bodies within the cel...

A blood disorder characterized by low levels of white blood cells (granular leukocytes) in the circulating blood. The condition is usually caused by certain drugs especially chemotherapy drugs....

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...

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...

Aicardi syndrome is an extremely rare genetic disorder. Almost all people with Aicardi syndrome are females. Individuals with Aicardi syndrome have agenesis of the corpus callosum, chorioretinal lacunae and seizures. Agenesis of the corpus callosu...

Osteopetrosis may be inherited as either a dominant or recessive trait and is marked by increased bone density, brittle bones, and, in some cases, skeletal abnormalities. Although symptoms may not initially be apparent in people with mild forms of...

The term albinism typically refers to oculocutaneous (ok-u-low-ku-TAY-nee-us) albinism (OCA) — a group of inherited disorders where there is little or no production of the pigment melanin. The type and amount of melanin your body produces de...

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 ...

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...

Reflex sympathetic dystrophy syndrome (RSDS), also known as complex regional pain syndrome, is a rare disorder of the sympathetic nervous system that is characterized by chronic, severe pain. The sympathetic nervous system is that part of the auto...

Reflex sympathetic dystrophy syndrome (RSDS), also known as complex regional pain syndrome, is a rare disorder of the sympathetic nervous system that is characterized by chronic, severe pain. The sympathetic nervous system is that part of the auto...

Alkaptonuria is an inherited condition that causes urine to turn black when exposed to air. Ochronosis, a buildup of dark pigment in connective tissues such as cartilage and skin, is also characteristic of the disorder. This blue-black pigmentatio...

MCT8-specific thyroid hormone cell transporter deficiency (THCT deficiency) is an inherited disorder that is characterized by severe mental retardation, an impaired ability to speak, diminished muscle tone (hypotonia), and/or movement abnormalitie...

MCT8-specific thyroid hormone cell transporter deficiency (THCT deficiency) is an inherited disorder that is characterized by severe mental retardation, an impaired ability to speak, diminished muscle tone (hypotonia), and/or movement abnormalitie...

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...

Alpers disease is a progressive neurologic disorder that begins during childhood and is complicated in many instances by serious liver disease. Symptoms include increased muscle tone with exaggerated reflexes (spasticity), seizures, and loss of co...

Tangier Disease is an inherited blood disorder involving decreased concentrations of fat compounds in the blood called high-density lipoproteins (sometimes called "good cholesterol"). Large amounts of these compounds may accumulate in certain orga...

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...

Amblyopia, also known as lazy eye, is a vision development disorder in which an eye fails to achieve normal visual acuity, even with prescription eyeglasses or contact lenses. It is the most common cause of vision problems in children. Amblyopia i...

Amenorrhea facts Amenorrhea refers to the absence of menstrual periods; it may be either primary (meaning a woman never developed menstrual periods) or secondary (absence of menstrual periods in a woman who was previously menstruati...

Amyotrophic lateral sclerosis facts Amyotrophic lateral sclerosis is a rapidly progressive, invariably fatal neurological disease that attacks the nerve cells responsible for controlling voluntary muscles. Amyotrophic late...

Anal cancer is a disease in which malignant (cancer) cells form in the tissues of the anus. The anus is the end of the large intestine, below the rectum, through which stool (solid waste) leaves the body. The anus is formed partly from the...

Anal cancer is a disease in which malignant (cancer) cells form in the tissues of the anus. The anus is the end of the large intestine, below the rectum, through which stool (solid waste) leaves the body. The anus is formed partly from the...

What is sickle cell anemia? Sickle cell anemia (sickle cell disease) is a disorder of the blood caused by an inherited abnormal hemoglobin (the oxygen-carrying protein within the red blood cells). The abnormal hemoglobin causes distorted (...

What is sickle cell anemia? Sickle cell anemia (sickle cell disease) is a disorder of the blood caused by an inherited abnormal hemoglobin (the oxygen-carrying protein within the red blood cells). The abnormal hemoglobin causes distorted (...

Anencephaly facts Anencephaly is an example of a neural tube defect, a condition that results from an error in the first weeks of embryonic development. In anencephaly, the bones of the skull and brain do not develop prope...

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...

Anisocoria is a condition in which the pupils of the eyes are different sizes. It is usually harmless and can be caused by a variety of factors, including medications, eye trauma, and neurological disorders....

Ankylosing spondylitis facts Ankylosing spondylitis belongs to a group of arthritis conditions that tend to cause chronic inflammation of the spine (spondyloarthropathies). Ankylosing spondylitis affects males two to three...

Anorexia nervosa facts Anorexia nervosa is a a psychiatric condition, which is part of a group of eating disorders. The cause of anorexia has not been definitively established, but self-esteem and body-image issues, societ...

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...

Apert syndrome, also known as acrocephalosyndactyly type I (ACS1), is a rare genetic disorder that is apparent at birth (congenital). The disorder is character-ized by distinctive malformations of the head that lead to distinctive facial features....

Sutton disease II is characterized by the recurring eruption of painful inflamed ulcers in the mouth (stomatitis). There may be multiple ulcers of varying sizes. These ulcers in the mouth are commonly called canker sores. Sutton disease II is also...

Aplasia Cutis Congenita is a rare disorder with a complicated pattern of inheritance. Babies are born with the absence of certain layer(s) of skin, most often on the scalp, but also on the trunk, and/or arms and legs. The affected area is typicall...

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....

Jejunal Atresia is a rare genetic disorder. Patients with this disorder are born with a partial absence of the fold of the stomach membrane that connects the small intestine to the back wall of the abdomen. As a result, one of the three portions o...

General DiscussionArachnoiditis is a disease characterized by an acute inflammatory stage that occurs in the dura (exterior) and the arachnoid (interior), two of the three membranes that cover and protect the brain, the spinal cord and th...

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....

Chikungunya is a rare viral infection transmitted by the bite of an infected mosquito. It is characterized by a rash, fever, and severe joint pain (arthralgias) that usually lasts for three to seven days. Because of its effect on the joints, Chiku...

Arcus senilis is a white or gray arc or circle that appears around the outer edge of the cornea of the eye. It is a normal part of aging and is usually seen in people over the age of 60. It is caused by a deposit of lipids in the cornea and is har...

Arginase deficiency is a rare inherited disorder characterized by complete or partial lack of the enzyme arginase. Arginase is one of six enzymes that play a role in the breakdown and removal of nitrogen from the body, a process known as the urea ...

Arginase deficiency is a rare inherited disorder characterized by complete or partial lack of the enzyme arginase. Arginase is one of six enzymes that play a role in the breakdown and removal of nitrogen from the body, a process known as the urea ...

Argininosuccinic aciduria is a rare inherited disorder characterized by deficiency or lack of the enzyme argininosuccinate lyase (ASL). Argininosuccinate lyase is one of six enzymes that play a role in the breakdown and removal of nitrogen from th...

Argininosuccinic aciduria is a rare inherited disorder characterized by deficiency or lack of the enzyme argininosuccinate lyase (ASL). Argininosuccinate lyase is one of six enzymes that play a role in the breakdown and removal of nitrogen from th...

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...

A heart arrhythmia (uh-RITH-me-uh) is an irregular heartbeat. Heart rhythm probl...

A heart arrhythmia (uh-RITH-me-uh) is an irregular heartbeat. Heart rhythm problems (heart arrhythmias) occur when the electrical signals that coordinate the heart's beats don't work properly. The faulty signalling causes the heart to beat too fas...

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...

Arterial chemotherapy infusion of the liver and chemoembolization of the liver (transarterial chemoembolization or TACE) are similar procedures that are used for the treatment of cancers in the liver. In both procedures, chemotherapy is injected i...

Polymyalgia rheumatica is a rare inflammatory disease characterized by muscle pain (myalgia), stiffness, and additional generalized systemic symptoms such as fatigue, low-grade fever, and/or a general feeling of ill health (malaise). Polymyalgia r...

Arthritis is the swelling and tenderness of one or more joints. The main symptoms of arthritis are joint pain and stiffness, which typically worsen with age. The most common types of arthritis are osteoarthritis and rheumatoid arthritis. O...

Arthritis is the swelling and tenderness of one or more joints. The main symptoms of arthritis are joint pain and stiffness, which typically worsen with age. The most common types of arthritis are osteoarthritis and rheumatoid arthritis. O...

Like many people with chronic ailments, sufferers of chronic arthritis are potentially vulnerable to proponents of heavily marketed "cure-all" treatments. These "quick fix" treatments are promoted as having great benefits, but in reality have no r...

Infectious arthritis is an inflammation of one or more joints that occurs as a result of infection by bacteria, viruses or, less frequently, fungi or parasites. The symptoms of Infectious arthritis depend upon which agent has caused the infection ...

Infectious arthritis is an inflammation of one or more joints that occurs as a result of infection by bacteria, viruses or, less frequently, fungi or parasites. The symptoms of Infectious arthritis depend upon which agent has caused the infection ...

Juvenile idiopathic arthritis, formerly known as juvenile rheumatoid arthritis, is the most common type of arthritis in children under the age of 16. Juvenile idiopathic arthritis can cause persistent joint pain, swelling and stiffness. So...

What is the definition of asbestos? Asbestos is a family of naturally occurring silica compounds (similar to, but not the same as, the silica of window glass and computer chips). These substances form fibers with varying shapes and sizes a...

Ascites is the accumulation of fluid (usually serous fluid which is a pale yellow and clear fluid) in the abdominal (peritoneal) cavity. The abdominal cavity is located below the chest cavity, separated from it by the diaphragm. Ascitic fluid can ...

Asperger’s syndrome, though no longer an official diagnosis, belongs to a group of neurodevelopment conditions known as autism spectrum disorder (ASD). Experts consider what was previously diagnosed as Asperger’s syndrome t...

A disorder in which a person's airways become inflamed, constrict, and bulge, as well as cre...

In childhood asthma, the lungs and airways become easily inflamed when exposed to certain triggers, such as inhaling pollen or catching a cold or other respiratory infection. Childhood asthma can cause bothersome daily symptoms t...

Astigmatism is a common eye condition that causes blurred vision due to an irregularly shaped cornea. It occurs when the cornea is curved more in one direction than the other, which causes light to be focused unevenly on the retina. This can cause...

OverviewArteriosclerosis occurs when the blood vessels that carry oxygen and nutrients from your heart to the rest of your body (arteries) become thick and stiff — sometimes restricting blood flow to your organs and tissues. Healthy art...

Arteriosclerosis occurs when the blood vessels that carry oxygen and nutrients from your heart to the rest of your body (arteries) become thick and stiff — sometimes restricting blood flow to your organs and tissues. Healthy arteries are fle...

Atopic dermatitis facts Atopic dermatitis is a type of eczema. The disease may be inherited and genetically determined. The patient's skin may be "super sensitive" to many irritants. Dry, scaly patches ...

Atrial fibrillation (A-fib) is an irregular and often very rapid heart rhythm (a...

Atrial fibrillation (A-fib) is an irregular and often very rapid heart rhythm (arrhythmia) that can lead to blood clots in the heart. A-fib increases the risk of stroke, heart failure and other he...

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 ...

Auditory Processing Disorder (APD) is a complex problem. The term is used by many people, in very different ways. There is research underway to help understand this disorder. There also is research to investigate therapies that will help individua...

Frey syndrome is a rare disorder that most often occurs as a result of surgery in the area near the parotid glands. The parotid glands are the largest salivary glands in the body located just below the ears on either side of the face. The main sym...

Autism spectrum disorder is a condition related to brain development that impacts how a person perceives and socializes with others, causing problems in social interaction and communication. The disorder also includes limited and repetitive patter...

Autism spectrum disorder is a condition related to brain development that impacts how a person perceives and socializes with others, causing problems in social interaction and communication. The disorder also includes limited and repetitive patter...

Romano-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 individuals may have no apparent...

Jervell and Lange-Nielsen syndrome (JLNS) is a rare inherited disorder characterized by deafness present at birth (congenital) occurring in association with abnormalities affecting the electrical system of the heart. The severity of cardiac sympto...

Osteonecrosis, also known as avascular necrosis, is a disease resulting from the temporary or permanent loss of the blood supply to the bones. Without blood, the bone tissue dies and causes the bone to collapse. If the process involves the bones n...

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...

Machado-Joseph Disease (MJD-III), also called spinocerebellar ataxia type III, is a rare, inherited, ataxia (lack of muscular control) affecting the central nervous system and characterized by the slow degeneration of particular areas of the brain...

Froehlich syndrome is a constellation of endocrine abnormalities believed to result from damage to the hypothalamus, a part of the brain where certain functions such as sleep cycles and body temperature are regulated. Froehlich syndrome appears to...

Infectious arthritis is an inflammation of one or more joints that occurs as a result of infection by bacteria, viruses or, less frequently, fungi or parasites. The symptoms of Infectious arthritis depend upon which agent has caused the infection ...

Bacterial keratitis is an infection of the cornea, the clear outer layer of the eye, caused by bacteria. Symptoms of bacterial keratitis include redness, pain, light sensitivity, blurred vision, and discharge from the eye. Treatment typically invo...

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...

Bacterial vaginosis (BV) is a common vaginal infection caused by an imbalance of bacteria in the vagina. Normally, the vagina contains a balance of good and harmful bacteria. However, when the harmful bacteria outnumber the good bacteria, it can l...

A balance disorder is a condition that makes you feel unsteady or dizzy, as if you are moving, spinning, or floating, even though you are standing still or lying down. Balance disorders can be caused by certain health conditions, medications, or a...

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...

Baller-Gerold Syndrome is a rare genetic disorder that is apparent at birth (congenital). The disorder is characterized by distinctive malformations of the skull and facial (craniofacial) area and bones of the forearms and hands. In in...

Balo Disease is a rare and progressive variant of multiple sclerosis. It usually first appears in adulthood, but childhood cases have also been reported. While multiple sclerosis typically is a disease that waxes and wanes, Balo Disease is differe...

A lower GI series, also known as a barium enema, barium enema procedure, barium enema X-ray or double-contrast barium enema, is an X-ray test in which a white liquid, called barium, is infused through a catheter (tube) inserted through the anus an...

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 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 ...

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...

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...

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 ...

Beckwith-Wiedemann syndrome (BWS) is a rare genetic overgrowth disorder. It is characterized by a wide spectrum of symptoms and physical findings that vary in range and severity from case to case. However, in many individuals, associated features ...

Bell's palsy (Bell palsy) is paralysis of the facial nerve of unknown cause. The diagnosis is made when no other cause can be identified. Although Bell's palsy is thought to be caused by a viral infection of the facial nerve, this hasn't been prov...

Bell's Palsy is a type of facial paralysis that results in the inability to control facial muscles on one side of the face. It is caused by damage or trauma to the facial nerve, which controls the muscles in the face. Symptoms of Bell's Palsy incl...

Polycystic ovary syndrome (PCOS) affects women and is a complex of symptoms that are not necessarily all present in all cases. Some, but not all, affected women have multiple cysts on the ovaries (polycystic ovaries). Other characteristics include...

Ivemark 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 abnormal arrangement of the inter...

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...

Kernicterus is a rare neurological disorder characterized by excessive levels of bilirubin in the blood (hyperbilirubinemia) during infancy. Bilirubin is an orange-yellow bile pigment that is a byproduct of the natural breakdown of hemoglobin in r...

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...

Black Eye is a mobile photography app that allows users to take and edit photos with a variety of filters, effects, and tools. It also includes features such as face recognition, portrait mode, and a variety of other editing tools....

Hairy tongue is an uncommon, benign condition that is also known as black hairy tongue or lingua nigra. It is characterized by abnormal elongation and blackish or dark brownish discoloration or "staining" of the thread-like elevations (filiform pa...

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...

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Blepharitis is an inflammation of the eyelids. It is a common condition that can cause redness, itching, burning, and a gritty sensation in the eyes. It can also cause the eyelids to become swollen, crusty, and flaky. Blepharitis is usually caused...

Benign essential blepharospasm (BEB) is a rare neurological disorder in which affected individuals experience involuntary muscle spasms and contractions of the muscles around the eyes. These spasms come and go (intermittent). Symptoms may begin as...

A blocked tear duct is a condition in which the tear ducts, which normally drain tears from the eyes, become blocked or narrowed. This can cause tears to build up in the eyes, leading to watery eyes, irritation, and other symptoms. Treatment for a...

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 ...

Bocavirus is a virus that causes the common cold and other respiratory infections. Cold, fever, runny nose, and cough are the most common symptoms. It can also cause gastroenteritis, or stomach flu, which can cause severe stomach and intestine irr...

Boil  A boil is a painful, pus-filled bump under your skin — the result of a bacterial infection of one or more hair follicles. Carbuncle  A carbuncle is a cluster of boils — painful, pus-filled bumps ...

What is bone cancer? What is metastatic bone cancer? Bone cancer is a cancer of the cells that make up the bones of the body. When cancer is found in bones, it has usually started in another organ or another location in the body and has sp...

What is bone cancer? What is metastatic bone cancer? Bone cancer is a cancer of the cells that make up the bones of the body. When cancer is found in bones, it has usually started in another organ or another location in the body and has sp...

Turner syndrome is a rare chromosomal disorder that affects females. The disorder is characterized by partial or complete loss (monosomy) of one of the X chromosomes. Turner syndrome is highly variable and can differ dramatically from one person t...

Borderline personality disorder is a personality disorder characterized by consistently problematic ways of thinking, feeling, and interacting, impulsivity, negative self-image and fear of abandonment, leading to difficulties with interpersonal re...

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...

Bowen disease is a rare skin disorder. Affected individuals develop a slow-growing, reddish scaly patch or plaque on the skin. Sun exposed areas of the skin are most often affected. Bowen disease only affects the outermost layer of the skin (epide...

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...

Parsonage-Turner syndrome is a relatively common condition characterized by inflammation of the network of nerves that control and supply (innervate) the muscles of the chest, shoulders, and arms (brachial plexus). Individuals with the condition f...

Parsonage-Turner syndrome is a relatively common condition characterized by inflammation of the network of nerves that control and supply (innervate) the muscles of the chest, shoulders, and arms (brachial plexus). Individuals with the condition f...

Cornelia de Lange syndrome (CdLS) is a rare genetic disorder that is apparent at birth (congenital). Associated symptoms and findings typically include delays in physical development before and after birth (prenatal and postnatal growth retardatio...

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...

Fukuyama type congenital muscular dystrophy (FCMD) is one of several forms of a rare type of muscular dystrophy known as congenital muscular dystrophy. It is inherited as an autosomal recessive trait. Symptoms of this disorder are apparent at birt...

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...

Branchio-oto-renal (BOR) syndrome is a rare disorder inherited as an autosomal dominant genetic trait. This disorder is characterized by pits or ear tags in front of the outer ear, abnormal passages from the throat to the outside surface of the ne...

Branchio-oculo-facial syndrome (BOFS) is a very rare genetic disorder that is apparent at birth (congenital). As of 2004, only about 50 cases of BOFS had been reported in the medical literature. The symptoms of most BOFS patients include the proli...

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...

Braxton Hicks contractions are the "false" labor pains that a pregnant woman might have before “true” labor. They’re your body's way of getting ready for the real thing. But they don’t mean labor has started or is about to ...

General DiscussionChagas Disease is a tropical infectious disease caused by the parasite Trypanosoma cruzi. It is transmitted by the bite of one of several species of blood-sucking insects or by blood transfusion. Acute Chagas Disease usu...

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...

Breast cancer is cancer that forms in the cells of the breasts. ...

Breast cancer is the most common cancer in pregnant women and tends to affect women in their mid-30s. Although only about 1 in every 1,000 pregnant women get breast cancer, the disease can be devastating to both the mother and her child -- so it i...

Younger women generally do not consider themselves to be at risk for breast cancer. Only 5 percent of all breast cancer cases occur in women under 40 years old. However, breast cancer can strike at any age, and all women should be aware of their p...

Introduction to Breast Cancer Recurrence Breast cancer can recur at any time, but most recurrences occur in the first three to five years after initial treatment. Breast cancer can come back as a local recurrence (in the treated breast or ...

Introduction to Breast Cancer Recurrence Breast cancer can recur at any time, but most recurrences occur in the first three to five years after initial treatment. Breast cancer can come back as a local recurrence (in the treated breast or ...

Facing a breast cancer diagnosis can be overwhelming. Your stress levels may skyrocket. You may worry about finances. And you may be asking yourself difficult questions, such as whether to write a living will. Education and supportive care can hel...

Facing a breast cancer diagnosis can be overwhelming. Your stress levels may skyrocket. You may worry about finances. And you may be asking yourself difficult questions, such as whether to write a living will. Education and supportive care can hel...

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...

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 ...

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 ...

Bronchitis is an infection that causes irritation and inflammation in the lungs' major airways (bronchi). Bronchitis is divided into two types: acute and chronic. Chronic bronchitis is a long-term condition that can reoccur. Long-term stress, such...

Bronchitis is an infection that affects the lungs' major airways (bronchi), causing irritation and inflammation. Bronchitis can be classified into two types: acute and long-term. Chronic bronchitis is a long-term problem that can come back. It is usu...

Buerger's disease (thromboangiitis obliterans) is a rare disease of the arteries and veins in the arms and legs. In Buerger's disease, your blood vessels become inflamed, swell and can become blocked with blood clots (thrombi). This eventu...

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...

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...

Bullous pemphigoid is an uncommon skin disease characterized by tense blisters on the surface of the skin. Occasionally, the inner lining tissue of the mouth, nasal passages, or conjunctivae of the eyes (mucous membrane tissue) can be involved. Th...

Bunions facts Bunions involve boney prominences and repositioning of the joints at the base of the big toes. Bunions most commonly affect the inner foot at the base of the big toe but also can affect the outside of the foo...

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...

Medullary Sponge Kidney is a rare disorder characterized by the formation of cystic malformations in the collecting ducts and the tubular structures within the kidneys (tubules) that collect urine. One or both kidneys may be affected. The initial ...

Clubfoot is a general term used to describe a group of deformities of the ankles and/or feet that are usually present at birth (congenital). The defect may be mild or severe and may affect one or both of the ankles and/or feet. Different forms of ...

A bursa is a thin fluid-filled sac that reduces friction forces between tissues of the body. Chronic (repeated or long-standing) inflammation of the bursa (bursitis) can lead to calcification of the bursa. This is referred to as "calcific bursitis...

A bursa is a thin fluid-filled sac that reduces friction forces between tissues of the body. Chronic (repeated or long-standing) inflammation of the bursa (bursitis) can lead to calcification of the bursa. This is referred to as "calcific bursitis...

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...

Campomelic syndrome is a rare congenital disorder in which multiple anomalies are present. It is characterized by bowing and angular shape of the long bones of the legs, especially the tibia; multiple minor anomalies of the face; cleft palate; oth...

Campomelic syndrome is a rare congenital disorder in which multiple anomalies are present. It is characterized by bowing and angular shape of the long bones of the legs, especially the tibia; multiple minor anomalies of the face; cleft palate; oth...

Gordon syndrome is an extremely rare disorder that belongs to a group of genetic disorders known as the distal arthrogryposes. These disorders typically involve stiffness and impaired mobility of certain joints of the lower arms and legs (distal e...

Camptomelic syndrome is a rare congenital disorder in which multiple anomalies are present. It is characterized by bowing and angular shape of the long bones of the legs, especially the tibia; multiple minor anomalies of the face; cleft palate; ot...

Camptomelic syndrome is a rare congenital disorder in which multiple anomalies are present. It is characterized by bowing and angular shape of the long bones of the legs, especially the tibia; multiple minor anomalies of the face; cleft palate; ot...

Camptomelic syndrome is a rare congenital disorder in which multiple anomalies are present. It is characterized by bowing and angular shape of the long bones of the legs, especially the tibia; multiple minor anomalies of the face; cleft palate; ot...

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...

Camurati-Engelmann disease is a rare genetic disorder characterized by progressive widening and malformation of the shafts of the long bones (diaphyseal dysplasia). Major symptoms may include bone pain, particularly in the legs; skeletal abnormali...

Canavan disease is rare genetic neurological disorder characterized by the spongy degeneration of the white matter in the brain. Affected infants may appear normal at birth, but usually develop symptoms between 3-6 months of age. Symptoms may incl...

Canavan disease is rare genetic neurological disorder characterized by the spongy degeneration of the white matter in the brain. Affected infants may appear normal at birth, but usually develop symptoms between 3-6 months of age. Symptoms may incl...

Canavan disease is rare genetic neurological disorder characterized by the spongy degeneration of the white matter in the brain. Affected infants may appear normal at birth, but usually develop symptoms between 3-6 months of age. Symptoms may incl...

Canavan disease is rare genetic neurological disorder characterized by the spongy degeneration of the white matter in the brain. Affected infants may appear normal at birth, but usually develop symptoms between 3-6 months of age. Symptoms may incl...

Endometrial cancer Open pop-up dialog box Close Endometrial cancer Endometrial cancer Endometrial cancer begins in the lining (endometrium) of the uterus. Endometrial cancer is a type of cancer that begins in the uterus. The uterus...

Endometrial cancer begins in the lining (endometrium) of the uterus. Endometrial cancer is a type of cancer that begins in the uterus. The uterus is the hollow, pear-shaped pelvic organ where fetal development occurs. Endometrial c...

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...

Pinta is a rare infectious tropical disease affecting the skin that is caused by the bacterium Treponema carateum, which is transmitted by direct, nonsexual contact. Pinta progresses through three distinct stages, which are characterized by variou...

Biotinidase deficiency (BTD) is a treatable, metabolic disorder that is the result of a low concentration, or complete lack, of the enzyme, biotinidase. Biotinidase deficiency is an inherited disorder in which the body is not able to properly proc...

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...

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...

The carotid arteries provide blood supply to the head. There are two common carotid arteries, located on each side of the neck, that divide into the internal and external carotid arteries. The external carotid artery provides blood supply to the s...

The carotid arteries provide blood supply to the head. There are two common carotid arteries, located on each side of the neck, that divide into the internal and external carotid arteries. The external carotid artery provides blood supply to the s...

Carotid artery disease is a condition in which the carotid arteries, which are the two main arteries that supply blood to the head and neck, become narrowed or blocked due to a buildup of plaque. This can lead to a stroke or transient ischemic att...

Cataracts are a clouding of the lens in the eye that affects vision. Most cataracts are related to aging. Symptoms may include blurry vision, poor night vision, sensitivity to light and glare, faded colors, halos around lights, and double vision i...

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

Cellulitis is a bacterial infection of the skin and underlying tissue. It is usually caused by bacteria such as Staphylococcus aureus or Streptococcus. Symptoms of cellulitis include redness, swelling, warmth, and pain in the affected area. If lef...

Central serous chorioretinopathy (CSC) is a disorder of the eye in which fluid accumulates beneath the retina, causing it to detach from the back of the eye. This can lead to blurred vision, distortion of vision, and blind spots. CSC is usually ca...

Cerebral palsy facts Cerebral palsy (CP) is an abnormality of motor function, the ability to move and control movements. Cerebral palsy is acquired at an early age, usually less than a year of age. Cerebral palsy...

What is the cervix? The cervix is part of a woman's reproductive system. It's in the pelvis. The cervix is the lower, narrow part of the uterus (womb). The cervix is a passageway: The cervix connects the uterus to th...

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 ...

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...

Chediak-Higashi syndrome (CHS) is a rare, inherited, complex, immune disorder of childhood (usually) characterized by abnormally pale skin and eyes (oculocutaneous albinism). Because the patient's white blood cells (leukocytes) are profoundly affe...

Chediak-Higashi syndrome (CHS) is a rare, inherited, complex, immune disorder of childhood (usually) characterized by abnormally pale skin and eyes (oculocutaneous albinism). Because the patient's white blood cells (leukocytes) are profoundly affe...

Hajdu-Cheney syndrome (HCS) is a rare, heritable disorder of connective tissue; only about 50 cases have been reported in the medical literature. The breakdown of bone (osteolysis), especially the outermost bones of the fingers and toes (acroosteo...

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...

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...

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...

Chickenpox (varicella) is a viral infection that causes an itchy rash with small, fluid-filled blisters. Chickenpox is highly contagious to people who haven't had the disease or been vaccinated against it. Before routine chickenpox vaccination, vi...

The virus is spread by mosquitoes and can cause severe joint pain. Chikungunya is viral infection that's spread among humans by mosquitoes that carry the virus. The infection is known for the sudden high fever and severe joint pain...

Chikungunya is a viral disease transmitted to humans by infected mosquitoes, specifically the Aedes aegypti and Aedes albopictus species. The most common symptoms of Chikungunya include fever, joint pain, headache, muscle pain, rash, and joint swe...

Chilblains (CHILL-blayns) are the painful inflammation of small blood vessels in your skin that occur in response to repeated exposure to cold but not freezing air. Also known as pernio, chilblains can cause itching, red patches, swelling and blis...

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...

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...

Childhood acute lymphoblastic leukemia (ALL) is a type of cancer in which the bone marrow makes too many immature lymphocytes (a type of white blood cell). Childhood acute lymphoblastic leukemia (also called acute lymphocytic leukemia or A...

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...

An epidemic is defined as occurring when "new cases of a certain disease, in a given human population during a given time period, substantially exceed what is expected based upon recent experience." Pediatric obesity has reached epidemic proportio...

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...

Cholera is an infectious disease caused by the bacterium Vibrio cholerae. It is typically spread through contaminated water or food and can cause severe diarrhea and dehydration. Cholera is a potentially life-threatening illness if not treated pro...

Choroidal neovascular membranes (CNVM) are abnormal blood vessels that grow from the choroid, a layer of blood vessels that lies beneath the retina. These abnormal vessels can cause vision loss by leaking fluid and blood into the macula, the area ...

Chronic Bronchitis is a type of COPD (chronic obstructive pulmonary disease). COPD is a lung infection and disease that can make breathing difficult and progressively worsen over time. Other than COPD, the most common type of COPD is emphysema. Th...

Cleft lip and palate are developmental defects of the upper lip and roof of the mouth that are present at birth (congenital malformations). Cleft lip and palate may occur separately and in combination. Both malformations o...

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),...

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...

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...

Cerebro-oculo-facio-skeletal (COFS) syndrome is a genetic degenerative disorder of the brain and spinal cord that begins before birth. The disorder is characterized by growth failure at birth and little or no neurological development, structural a...

Walker-Warburg syndrome (WWS) is a rare multisystem disorder characterized by muscle, brain and eye abnormalities, often leading to death in the first weeks of life. However, the specific symptoms and severity of WWS can vary greatly from case to ...

Coffin-Lowry syndrome is a rare genetic disorder characterized by mental retardation; abnormalities of the head and facial (craniofacial) area; large, soft hands with short, thin (tapered) fingers; short stature; and/or various skeletal abnormalit...

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 ...

Coffin-Lowry syndrome is a rare genetic disorder characterized by mental retardation; abnormalities of the head and facial (craniofacial) area; large, soft hands with short, thin (tapered) fingers; short stature; and/or various skeletal abnormalit...

Cerebro-oculo-facio-skeletal (COFS) syndrome is a genetic degenerative disorder of the brain and spinal cord that begins before birth. The disorder is characterized by growth failure at birth and little or no neurological development, structural a...

Cold antibody hemolytic anemia (CAHA) is a rare autoimmune disorder characterized by the premature destruction of red blood cells (rbcs) by the body's natural defenses against invading organisms (antibodies). Normally, the red blood cells have a l...

For many parents, there is nothing more stressful than listening to an inconsolably crying newborn. Colic generally leads to long stretches of such crying. It can be a very difficult for parents, friends, and family who are already dealing with on...

Colitis means inflammation of the colon. The colon, also known as the large intestine or large bowel, constitutes the last part of the digestive tract. The colon is a long, muscular tube that receives digested food from the small intestine. It rem...

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. ...

Coloboma is a congenital eye defect that occurs when part of the eye does not form properly during development. It is characterized by a gap in one or more parts of the eye, such as the iris, retina, choroid, or optic disc. Coloboma can cause visi...

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...

Color blindness, also known as color vision deficiency, is a condition in which a person is unable to distinguish certain colors or shades of colors. It is usually inherited and affects both eyes equally. People with color blindness may have diffi...

Compartment syndrome describes increased pressure within a muscle compartment of the arm or leg. It is most often due to injury, such as fracture, that causes bleeding in a muscle, which then causes increased pressure in the muscle. This pressure ...

What are congenital heart defects? Congenital (kon-JEN-ih-tal) heart defects are problems with the heart's structure that are present at birth. These defects can involve: The interior walls of the heart The valves ...

What is congestive heart failure (CHF)? Heart failure describes the inability or failure of the heart to adequately meet the needs of organs and tissues for oxygen and nutrients. This decrease in cardiac output, the amount of blood that th...

Conjunctivitis, commonly known as pink eye, is an inflammation of the conjunctiva, the thin, transparent membrane that lines the inner surface of the eyelid and covers the white part of the eye. It is usually caused by a bacterial or viral infecti...

Mixed connective tissue disease facts Connective tissues are the framework of the cells of the body. Mixed connective tissue disease is an "overlap" combination of connective tissue diseases. Diagnosis of mixed c...

Contact dermatitis facts Contact dermatitis is a rash that occurs at the site of exposure to a substance capable of producing an allegic or irritant skin response. Contact dermatitis can be caused by noxious, irritating su...

Contact lens-related eye infections are infections of the eye caused by the improper use of contact lenses. These infections can range from mild to severe and can cause a variety of symptoms, including redness, itching, burning, and blurred vision...

COPD is a chronic lung disease that results in obstructed airflow from the lungs. Asthmatics have difficulty breathing, cough, cough up mucus (sputum), and wheeze. It is most commonly caused by long-term exposure to irritating particles or gases, ...

COPD is a long-term lung disease that causes blocked airflow from the lungs. People who have asthma have trouble breathing, cough, cough up mucus (sputum), and wheeze. It is most often caused by exposure to irritating particles or gases over a long p...

Corneal abrasion is a condition in which the outer layer of the cornea (the clear, dome-shaped surface that covers the front of the eye) is scratched or scraped. It is a common eye injury that can cause pain, redness, tearing, and light sensitivit...

Corneal dystrophies are a group of inherited eye disorders that cause progressive changes to the cornea, the clear outer layer of the eye. These disorders can cause vision loss and other eye problems. Symptoms vary depending on the type of corneal...

Corneal laceration is a tear or cut in the cornea, the clear, dome-shaped surface that covers the front of the eye. It is usually caused by a sharp object, such as a fingernail, a piece of metal, or a tree branch. Corneal lacerations can cause pai...

A corneal ulcer is an open sore on the cornea, the clear dome-shaped surface that covers the front of the eye. It is usually caused by an infection, such as bacterial, viral, or fungal, or by an injury to the eye. Symptoms of a corneal ulcer inclu...

The inflammation of the joints that connect the ribs to the breast bone is known as costochondritis. Costochondritis can develop as a result of genetics, viruses, or even an accident. Costochondritis can be a separate medical condition or a sympto...

COVID-19 is a highly contagious respiratory illness caused by the novel coronavirus SARS-CoV-2. It was first identified in Wuhan, China in late 2019 and has since spread globally, leading to a pandemic. Symptoms of COVID-19 can range from mild to ...

Carbamoyl phosphate synthetase I deficiency (CPSID) is a rare inherited disorder characterized by complete or partial lack of the carbamoyl phosphate synthetase (CPS) enzyme. This is one of five enzymes that play a role in the breakdown and remova...

Carnitine palmitoyltransferase 1A deficiency (CPT1A) is characterized by a sudden onset of liver failure and damage to the nervous system resulting from liver failure (hepatic encephalopathy), usually associated with fasting or illness. CPT1A defi...

Cradle cap causes crusty or oily scaly patches on a baby's scalp. The condition isn't painful or itchy. But it can cause thick white or yellow scales that aren't easy to remove. Cradle cap usually clears up on its own in a few months. Home...

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...

Encephaloceles are rare birth defects associated with skull defects characterized by partial lacking of bone fusion leaving a gap through which a portion of the brain sticks out (protrudes). In some cases, cerebrospinal fluid or the membranes that...

Scott craniodigital syndrome is a condition that has only been found in two families. The manifestations include unusual head shape, growth and developmental delay, and mild webbing between the fingers and toes (syndactyly)...

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...

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...

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...

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 ...

Baller-Gerold Syndrome is a rare genetic disorder that is apparent at birth (congenital). The disorder is characterized by distinctive malformations of the skull and facial (craniofacial) area and bones of the forearms and hands. In in...

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...

Oculocerebral Syndrome with Hypopigmentation is an extremely rare inherited disorder characterized by the lack of normal color (hypopigmentation) of the skin and hair and abnormalities of the central nervous system that affect the eyes and certain...

Gianotti-Crosti Syndrome is a rare skin disease affecting children between the ages of nine months and nine years. Major symptoms may include blisters on the skin of the legs, buttocks and arms. The disorder is usually preceded by a viral infectio...

Croup is a common childhood illness that causes swelling of the upper respiratory tract. This can be recognised by a change in tone of voice and a distinctive "croupy" cough that sounds like a seal or barking. Croup is caused by a variety of virus...

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 ...

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...

Cryptococcus is a fungus that is found in soil all over the world, usually in association with bird droppings. Cryptococcus neoformans is the most common Cryptococcus species that causes illness in humans. Cryptococcus gattii, a less common specie...

An interstitial lung disease occurs when there is cryptogenic fibrous alveolitis in the lungs (or ILD for short). They have an impact on the tissues that support the air sacs in the lungs, making it difficult for them to take in as much air as the...

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, ...

Atypical mole syndrome, also called dysplastic nevus syndrome, is a disorder of the skin characterized by the presence of many mole-like tumors (nevi). Most people have 10-20 moles over their bodies. People with this syndrome often have more than ...

Cutis laxa is rarely encountered and may occur in several inherited (congenital) forms or come about in the course of another disorder (acquired). It is a connective tissue disorder characterized by skin that is loose (lax), hanging, wrinkled, and...

De Barsy syndrome is a rare, autosomal recessive genetic disorder, the main characteristics of which are a prematurely aged-looking face (progeria), cloudy corneas, short stature, and mental retardation. The condition is expressed in variable pres...

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 neutropenia is a rare blood disorder characterized by recurrent episodes of abnormally low levels of certain white blood cells (neutrophils) in the body. Neutrophils are instrumental in fighting off infection by surrounding and destroying b...

  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, ...

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...

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, ...

Cysticercosis (pork tapeworm infection) facts Cysticercosis is a parasitic disease caused by ingesting the eggs of the pork tapeworm, Taenia solium. Humans are infected by ingesting raw or undercooked pork, and cysticercos...

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...

Best vitelliform macular dystrophy is an autosomal dominant genetic form of macular degeneration that usually begins in childhood or adolescence and slowly progresses to affect central vision. The age of onset and severity of vision loss are highl...

Cyst facts Cysts are closed sac-like or capsule structures that may be filled with semisolid material, gaseous material, or liquid. There are several causes of cysts, including genetic, infectious, and other causes that resu...

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...

Cytomegalovirus infection (CMV) is a viral infection that rarely causes obvious illness. The virus that causes CMV is part of the herpes virus family and, like other herpes viruses, may become dormant for a period of time and then be reactivated. ...

Cytomegalovirus (CMV) is a common virus that belongs to the herpesvirus family. It can infect people of all ages and is usually harmless to those with a healthy immune system. However, it can cause serious complications in individuals with weakene...

Cytomegalovirus retinitis is an infection of the retina caused by the cytomegalovirus (CMV). It is a common cause of vision loss in people with weakened immune systems, such as those with HIV/AIDS. Symptoms of CMV retinitis include blurred vision,...

General DiscussionThe 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 inclu...

Opsoclonus-myoclonus syndrome (OMS) is a paraneoplastic neurological disorder. It is characterized by associated ocular, motor, behavioral, sleep, and language disturbances. The onset is usually abrupt, often severe, and can become chronic....

Dandy-Walker malformation (DWM) is a brain malformation that occurs during embryonic development of the cerebellum and 4th ventricle. The cerebellum is the area of the brain that helps coordinate movement, and is also involved with cognition and b...

Dandy-Walker malformation (DWM) is a brain malformation that occurs during embryonic development of the cerebellum and 4th ventricle. The cerebellum is the area of the brain that helps coordinate movement, and is also involved with cognition and b...

Dandy-Walker malformation (DWM) is a brain malformation that occurs during embryonic development of the cerebellum and 4th ventricle. The cerebellum is the area of the brain that helps coordinate movement, and is also involved with cognition and b...

Dandy-Walker malformation (DWM) is a brain malformation that occurs during embryonic development of the cerebellum and 4th ventricle. The cerebellum is the area of the brain that helps coordinate movement, and is also involved with cognition and b...

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. ...

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...

Subacute sclerosing panencephalitis (SSPE) is a progressive neurological disorder characterized by inflammation of the brain (encephalitis). The disease may develop due to reactivation of the measles virus or an inappropriate immune response to th...

Subacute sclerosing panencephalitis (SSPE) is a progressive neurological disorder characterized by inflammation of the brain (encephalitis). The disease may develop due to reactivation of the measles virus or an inappropriate immune response to th...

De Barsy syndrome is a rare, autosomal recessive genetic disorder, the main characteristics of which are a prematurely aged-looking face (progeria), cloudy corneas, short stature, and mental retardation. The condition is expressed in variable pres...

De Barsy syndrome is a rare, autosomal recessive genetic disorder, the main characteristics of which are a prematurely aged-looking face (progeria), cloudy corneas, short stature, and mental retardation. The condition is expressed in variable pres...

Cornelia de Lange syndrome (CdLS) is a rare genetic disorder that is apparent at birth (congenital). Associated symptoms and findings typically include delays in physical development before and after birth (prenatal and postnatal growth retardatio...

De Sanctis-Cacchione syndrome is an extremely rare disorder characterized by the skin and eye symptoms of xeroderma pigmentosum (XP) occurring in association with neurological abnormalities, mental retardation, unusually short stature (dwarfism), ...

Locked-in syndrome is a rare neurological disorder in which there is complete paralysis of all voluntary muscles except for the ones that control the movements of the eyes. Individuals with locked-in syndrome are conscious and awake, but have no a...

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...

General DiscussionJervell and Lange-Nielsen syndrome (JLNS) is a rare inherited disorder characterized by deafness present at birth (congenital) occurring in association with abnormalities affecting the electrical system of the heart. The...

Peeling skin syndrome is a rare inherited skin disorder characterized by painless, continual, spontaneous skin peeling (exfoliation). Other findings may include blistering and/or reddening of the skin (erythema) and itching (pruritus). Peeling ski...

Huntington's disease is a genetic, progressive, neurodegenerative disorder characterized by the gradual development of involuntary muscle movements affecting the hands, feet, face, and trunk and progressive deterioration of cognitive processes and...

Degenerative disc disease and sciatica facts The discs of the spine serve as "cushions" between each vertebral segment. The discs are designed somewhat like a jelly donut. Degeneration (deterioration) of the disc...

Degos disease is a very rare disease in which small and medium-sized arteries become blocked, preventing proper blood flow to the affected areas. You may also develop skin lesions, which can last from weeks to years depending on the extent of the ...

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...

Central pain syndrome is a neurological disorder caused by damage to the central nervous system (CNS). Common symptoms include pain and loss of sensation, usually in the face, arms and/or legs. Pain is often constant and can be mild, moderate, or ...

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 that involve either...

Depression is a mood disorder that causes a persistent feeling of sadness and loss of interest. Also called major depressive disorder or clinical depression, it affects how you feel, think and behave and can lead to a variety of emotional and phys...

Clinical depression in the elderly is common. Although, that doesn't mean it's normal. Late-life depression affects about 6 million Americans age 65 and older. But only 10% receive treatment for depression. The likely reason is that the elderly of...

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...

Urine tests for diabetes facts Urine tests may be done in people with diabetes to evaluate severe hyperglycemia (severe high blood sugar) by looking for ketones in the urine. Ketones are a metabolic product produced when fat...

Urine tests for diabetes facts Urine tests may be done in people with diabetes to evaluate severe hyperglycemia (severe high blood sugar) by looking for ketones in the urine. Ketones are a metabolic product produced when fat...

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 eye disease is a group of eye problems that can occur in people with diabetes. These eye problems can include diabetic retinopathy, cataracts, and glaucoma. Diabetic retinopathy is the most common form of diabetic eye disease and is cause...

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

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

Neuropathy is damage to nerves, and diabetic neuropathy is damage to nerves that occurs as a result of diabetes. Diabetes is thought to damage nerves as a result of prolonged elevated levels of blood glucose. Diabetic neuropathy can affect differe...

Diabetic retinopathy is a complication of diabetes that affects the eyes. It occurs when high blood sugar levels damage the blood vessels in the retina, the light-sensitive tissue at the back of the eye. This can lead to vision loss or blindness. ...

Blackfan-Diamond anemia (BDA) is a rare blood disorder that is caused by a failure of the bone marrow to generate enough red blood cells. It is characterized by deficiency of red blood cells at birth (congenital hypoplastic anemia) as well as slow...

Hereditary multiple osteochondromas (HMO) is a rare genetic disorder characterized by multiple benign (noncancerous) bone tumors that are covered by cartilage (osteochondromas), often on the growing end (metaphysis) of the long bones of the legs, ...

Camurati-Engelmann disease is a rare genetic disorder characterized by progressive widening and malformation of the shafts of the long bones (diaphyseal dysplasia). Major symptoms may include bone pain, particularly in the legs; skeletal abnormali...

Travelers' diarrhea facts Travelers' diarrhea is a gastrointestinal illness that occurs in travelers. Travelers' diarrhea usually is caused by eating food contaminated with bacteria or, less commonly, with parasites or vir...

Travelers' diarrhea facts Travelers' diarrhea is a gastrointestinal illness that occurs in travelers. Travelers' diarrhea usually is caused by eating food contaminated with bacteria or, less commonly, with parasites or vir...

Diastrophic dysplasia, which is also known as disastrophic dwarfism, is a rare disorder that is present at birth (congenital). The range and severity of associated symptoms and physical findings may vary greatly from case to case. However, the dis...

Diastrophic dysplasia, which is also known as disastrophic dwarfism, is a rare disorder that is present at birth (congenital). The range and severity of associated symptoms and physical findings may vary greatly from case to case. However, the dis...

Diastrophic dysplasia, which is also known as disastrophic dwarfism, is a rare disorder that is present at birth (congenital). The range and severity of associated symptoms and physical findings may vary greatly from case to case. However, the dis...

Bejel is an infectious disease that is rare in the United States but common in certain parts of the world. The infection is very similar to syphilis but is not sexually transmitted. Most frequently, transmission is by means of non-sexual skin cont...

Wolfram syndrome is the inherited association of childhood-onset diabetes mellitus and progressive-onset optic atrophy. All people affected by Wolfram syndrome have juvenile-onset diabetes mellitus and degeneration of the optic nerve (optic atroph...

The diencephalic syndrome is a very rare neurological disorder characterized by failure to thrive, abnormal thinness (emaciation), amnesia, intense sleepiness, unusual eye position and sometimes blindness. It is normally seen in infancy or early c...

The diencephalic syndrome is a very rare neurological disorder characterized by failure to thrive, abnormal thinness (emaciation), amnesia, intense sleepiness, unusual eye position and sometimes blindness. It is normally seen in infancy or early c...

Diphtheria is a serious bacterial infection that usually affects the mucous membranes of the throat and nose. It is caused by the bacterium Corynebacterium diphtheriae and is spread through respiratory droplets or direct contact with an infected p...

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...

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...

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...

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...

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 ...

The term dolichostenomelia comes from the Greek words 'dolichos,"steno,' and'melia,' which mean long, narrow, and of the limbs, respectively. It is a human condition in which a person's limbs are unusually long and narrow. It mostly affects connec...

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...

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 ...

Down syndrome is a genetic disorder and the most common autosomal chromosome abnormality in humans, where extra genetic material from chromosome 21 is transferred to a newly formed embryo. These extra genes and DNA cause changes in the development...

Dry eye is a condition in which the eyes do not produce enough tears or the tears evaporate too quickly. This can cause irritation, redness, and a feeling of dryness in the eyes. Dry eye can be caused by a variety of factors, including environment...

Dry skin facts Dry skin is a very common condition that causes small fine flakes and dry patches. Itching is one of the most common symptoms of dry skin. Scratching may be hard to resist. Dry skin is mo...

Dubin Johnson Syndrome is a rare genetic liver disorder that tends to affect people of Middle Eastern Jewish heritage disproportionately to other groups. It appears to be associated with clotting factor VII in this population. Symptoms may include...

Dubowitz syndrome is a very rare genetic and developmental disorder involving multiple congenital (inherited) anomalies including but not limited to: (1) growth failure/short stature; (2) unusual but characteristic facial features; (3) a small hea...

Brachial plexus palsy, also known as Erb's palsy, is a paralysis or weakness of the arm caused by an injury to one or more nerves that control and supply the muscles of the shoulder and upper extremities (upper brachial plexus). It is more commonl...

Dermatitis herpetiformis, also known as Duhring disease, is a rare, chronic, skin disorder characterized by the presence of groups of severely itchy (pruritic) blisters and raised skin lesions (papules). These are more common on the knees, elbows,...

Duodenal atresia or stenosis is a rare congenital digestive disorder that usually occurs for no apparent reason (sporadically). However, a few cases of duodenal atresia have been inherited as an autosomal recessive genetic trait. Duode...

Though ulcers often heal on their own, you shouldn't ignore their warning signs. If not properly treated, ulcers can lead to serious health problems, including: Bleeding Perforation (a hole through the wall of the stomach)...

Trisomy 5p is a rare chromosomal disorder in which all or a portion of the short arm (p) of chromosome 5 (5p) appears three times (trisomy) rather than twice in cells of the body. Often the duplicated portion of 5p (trisomy) is due to a complex re...

Chromosome 9, Trisomy 9p is a rare chromosomal syndrome in which a portion of the 9th chromosome appears three times (trisomy) rather than twice in cells of the body. The trisomy may involve a portion of the short arm (9p), the entire short arm, o...

Frey syndrome is a rare disorder that most often occurs as a result of surgery in the area near the parotid glands. The parotid glands are the largest salivary glands in the body located just below the ears on either side of the face. The main sym...

Dupuytren's contracture facts A Dupuytren's contracture is a localized scar tissue formation in the palm. The precise cause of a Dupuytren's contracture is not known. A Dupuytren's contracture is sometimes inheri...

Meningiomas are benign, slow-growing tumors, classified as brain tumors, but actually growing in the three protective membranes that surround the brain (meninges). Sometimes they cause thickening or thinning of adjoining skull bones. Meningiomas d...

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...

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, ...

Dyschondrosteosis is a very rare inherited disorder characterized by unusually shortened, bowed bones in the forearms (radius and ulna), abnormal deviation of the wrist toward the thumb side of the hand due to shortening of the radius and dislocat...

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...

A type of dermatitis, dyshidrotic eczema is much more common among women. Dyshidrotic eczema, also known as dyshidrosis or pompholyx, is a type of eczema that causes a blistering rash on the hands or feet, especially the fingers, palms, an...