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 ...

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...

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...

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...

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...

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...

Campylobacteriosis is an infection caused by bacteria y...

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...

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...

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...

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...

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 ...

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...

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...

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...

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...

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 ...

Achalasia is a rare disorder of the esophagus, the tube that carries food from the throat to the stomach. It is characterized by enlargement of the esophagus, impaired ability to push food down toward the stomach (peristalsis), and failure of the ...

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 ...

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

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

Galactosemia is a rare, hereditary disorder of carbohydrate metabolism that affects the body's ability to convert galactose (a sugar contained in milk, including human mother's milk) to glucose (a different type of sugar). Galactose is converted t...

Hypogammaglobulinemia is a problem with the immune system that prevents it from making enough antibodies called immunoglobulins. Antibodies are proteins that help your body recognize and fight off foreign invaders like bacteria, viruses, and fungi...

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

Andersen disease belongs to a group of rare genetic disorders of glycogen metabolism, known as glycogen storage diseases. Glycogen is a complex carbohydrate that is converted into the simple sugar glucose for the body's use as energy. Glycogen sto...

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...

Chronic granulomatous disease (CGD) is a rare inherited primary immune deficiency disorder that affects certain white blood corpuscles (neutrophils, monocytes, macrophages, eosinophils). The disorder is characterized by an inability to resist repe...

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...

Hereditary sensory and autonomic neuropathy type II (HSAN2) is a rare genetic disorder that usually begins in childhood by affecting the nerves that serve the lower legs and feet and the lower arms and hands. Symptoms start with inflamed fingers o...

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

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

Lamellar ichthyosis is a rare genetic skin disorder. In lamellar ichthyosis, the skin cells are produced at a normal rate, but they do not separate normally at the surface of the outermost layer of skin (stratum corneum) and are not shed as quickl...

The WAS-related disorders are a spectrum of conditions affecting the immune system that are caused by mutations in the WAS gene. These disorders include Wiskott-Aldrich syndrome, X-linked thrombocytopenia and X-linked congenital neutropenia. The W...

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

Hyper-IgM Syndrome (HIM) is a rare genetic (primary) immunodeficiency disorder that is typically inherited as an X-linked recessive genetic trait. Symptoms and physical findings associated with the disorder usually become apparent in the first or ...

Agammaglobulinemia is a group of inherited immune deficiencies characterized by a low concentration of antibodies in the blood due to the lack of particular lymphocytes in the blood and lymph. Antibodies are proteins (immunoglobulins, (IgM), (IgG)...

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

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...

Kugelberg Welander syndrome is a milder type of spinal muscular atrophy. It is a rare inherited neuromuscular disorder characterized by wasting and weakness in the muscles of the arms and legs, leading to walking difficulties in, and eventual loss...

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...

Leukoedema is a benign condition that affects the mucous membranes inside the mouth, causing them to appear white or grayish in color. It is often mistaken for oral thrush or leukoplakia, but it is actually a harmless and temporary condition that ...

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

Hereditary lymphedema is a genetic developmental disorder affecting the lymphatic system. It is characterized by swelling (edema) of certain parts of the body. The lymphatic system is a circulatory network of vessels, ducts, and nodes that filter ...

Dextrocardia with Situs Inversus is a rare heart condition characterized by abnormal positioning of the heart. In this condition, the tip of the heart (apex) is positioned on the right side of the chest. Additionally, the position of the heart cha...

Hereditary sensory and autonomic neuropathy type II (HSAN2) is a rare genetic disorder that usually begins in childhood by affecting the nerves that serve the lower legs and feet and the lower arms and hands. Symptoms start with inflamed fingers o...

Flesh-eating bacteria (necrotizing fasciitis) is a rare infection of the skin and tissues below it. It can be deadly if not treated quickly. Necrotizing fasciitis spreads quickly and aggressively in an infected person. It causes tissue dea...

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

Osteonecrosis of the jaw (ONJ) is a rare condition in which the bone tissue in the jaw fails to heal after minor trauma, such as a tooth extraction or dental surgery, leading to the death of the bone tissue. This can result in pain, swelling, infe...

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...

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

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

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

Chromosome 21 Ring is a rare chromosomal disorder in which the affected infant has a breakage of chromosome 21 at both ends, and the ends of the chromosome join together to form a ring. The amount of genetic material lost at the two ends of the ch...

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

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...

Kugelberg Welander syndrome is a milder type of spinal muscular atrophy. It is a rare inherited neuromuscular disorder characterized by wasting and weakness in the muscles of the arms and legs, leading to walking difficulties in, and eventual loss...

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

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

Acquired aplastic anemia is a rare disorder caused by profound, almost complete bone marrow failure. Bone marrow is the spongy substance found in the center of the bones of the body, in adults mainly the spine, pelvis, and large bones of the legs....

General DiscussionCor triatriatum is an extremely rare congenital (present at birth) heart defect. Normally, the human heart has four chambers of which two are the atria. These two are separated from each other by a partition (septum) cal...

Trichinosis (trik-ih-NO-sis), sometimes called trichinellosis (trik-ih-nuh-LOW-sis), is a type of roundworm infection. These roundworm parasites (trichinella) use a host body to live and reproduce. These parasites infect animals such as bears, cou...

Type 2 diabetes is an impairment in the way the body regulates and uses sugar (glucose) as a fuel. This long-term (chronic) condition results in too much sugar circulating in the bloodstream. Eventually, high blood sugar levels can lead to disorde...

Type 2 diabetes is an impairment in the way the body regulates and uses sugar (glucose) as a fuel. This long-term (chronic) condition results in too much sugar circulating in the bloodstream. Eventually, high blood sugar levels can lead to disorde...

What is the urethra? The urethra is the opening that allows urine to leave the bladder. In men, the urethra is a thin tube-like structure that starts from the lower opening of the bladder and traverses the entire length of the penis. In wo...

The WAS-related disorders are a spectrum of conditions affecting the immune system that are caused by mutations in the WAS gene. These disorders include Wiskott-Aldrich syndrome, X-linked thrombocytopenia and X-linked congenital neutropenia. The W...