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 ...

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...

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...

  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...

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....

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...

Conradi-Hunermann syndrome is a rare genetic disorder characterized by skeletal malformations, skin abnormalities, cataracts and short stature. The specific symptoms and severity of the disorder may vary greatly from one individual to another. Con...

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

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

Pantothenate kinase-associated neurodegeneration (PKAN), formerly called Hallervorden-Spatz syndrome, is a rare, inherited neurological movement disorder characterized by the progressive degeneration of the nervous system (neurodegenerative disord...

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....

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

Moyamoya syndrome is a progressive disorder that affects the blood vessels in the brain (cerebrovascular). It is characterized by the narrowing (stenosis) and/or closing (occlusion) of the carotid artery inside the skull, the major artery that del...

Moyamoya syndrome is a progressive disorder that affects the blood vessels in the brain (cerebrovascular). It is characterized by the narrowing (stenosis) and/or closing (occlusion) of the carotid artery inside the skull, the major artery that del...

The Mucopolysaccharidoses (MPS Disorders) are a group of rare genetic disorders caused by the deficiency of one of the lysosomal enzymes, resulting in an inability to metabolize complex carbohydrates (mucopolysaccharides) into simpler molecules. H...

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...

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....

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....

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....

Pantothenate kinase-associated neurodegeneration (PKAN), formerly called Hallervorden-Spatz syndrome, is a rare, inherited neurological movement disorder characterized by the progressive degeneration of the nervous system (neurodegenerative disord...

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

Smith-Magenis syndrome is characterized by particular facial features, developmental delays, mental retardation and behavioral abnormalities. The facial features include a broad square-shaped face, an abnormally short, broad head (brac...

Smith-Magenis syndrome is characterized by particular facial features, developmental delays, mental retardation and behavioral abnormalities. The facial features include a broad square-shaped face, an abnormally short, broad head (brac...

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

Large arteries Open pop-up dialog box Close Large arteries Large arteries Takayasu's arteritis is a form of vasculitis — inflammation of the blood vessels — that damages the large arteries, especially the aorta. Chamber...

Weil syndrome, a rare infectious disorder, is a severe form of the bacterial infection caused by Leptospira bacteria known as leptospirosis. Weil syndrome is characterized by dysfunction of the kidneys and liver, abnormal enlargement of the liver ...