Jugular foramen syndrome (JFS), often called Vernet syndrome, is a rare skull-base condition in which anything that irritates or squashes the jugular ...

Joubert syndrome (JS) is a rare, inherited condition in which the back part of a baby’s brain—the cerebellar vermis—and the adjoining brain-stem fail to finish ...

Jaffe–Campanacci syndrome (JCS) is an extremely rare bone-and-skin condition in which a child or young adult develops many non-ossifying fibromas—soft, fibrous ...

Incontinentia pigmenti (IP) is a rare, X-linked dominant genetic condition that mainly affects girls because boys who inherit the faulty gene (IKBKG/NEMO) ...

Horner’s syndrome (sometimes called oculosympathetic paresis) is a cluster of eye- and face-related changes that appear when the three-neuron sympathetic nerve ...

Hereditary hemorrhagic telangiectasia—also called Osler-Weber-Rendu disease—is a rare, lifelong, inherited condition that makes some blood vessels grow in an ...

Hemimegalencephaly (HME) is a rare birth defect in which one half of the brain grows abnormally large and disorganized. The over-growth distorts the normal ...

Heerfordt syndrome is a rare, face-and-eye-centred form of the systemic disease sarcoidosis. In sarcoidosis the body’s immune system builds tiny clusters of ...

HEC syndrome is an extremely rare birth disorder in which H = communicating Hydrocephalus (excess fluid around the brain), E = Endocardial Fibroelastosis ...

Harlequin syndrome (HS) is a rare problem of the body’s “automatic” (autonomic) nervous system. In HS, the tiny sympathetic nerves that normally make both ...

Hamanishi-Ueba-Tsuji syndrome is an extremely rare hereditary motor-and-sensory neuropathy first described in Japan in 1985. Babies are born with absent or ...

Miller Fisher Syndrome is a rare, nerve-related illness that belongs to the Guillain-Barré Syndrome (GBS) family. While classic GBS mostly weakens the limbs, ...

Acute Motor-Sensory Axonal Neuropathy (often shortened to AMSAN) is one of the rarer, more aggressive “axonal” forms of Guillain-Barré syndrome (GBS). In ...

Acute Motor Axonal Neuropathy—usually shortened to AMAN—is a fast-moving, immune-related attack on the motor (movement-controlling) portions of the peripheral ...

Acute Inflammatory Demyelinating Polyradiculoneuropathy—usually shortened to AIDP—is an autoimmune attack on the insulating myelin sheath that normally helps ...

Guillain–Barré syndrome is an uncommon but serious autoimmune nerve disorder in which the body’s own immune system suddenly turns against the peripheral ...

Gradenigo’s syndrome is the name doctors give to a very specific complication of a middle-ear infection. When bacteria in an episode of acute or chronic otitis ...

Gómez–López-Hernández syndrome (GLHS)—also called cerebello-trigeminal-dermal dysplasia—is an extremely rare neuro-cutaneous disorder first described in 1979. ...

Gillespie syndrome (GS) is an ultra-rare genetic disorder that blends partial or “scalloped” aniridia, congenital or slowly progressive cerebellar ataxia, and ...

Gerstmann–Sträussler–Scheinker syndrome is a very rare, inherited brain disease belonging to the group of human prion disorders. In prion diseases, a perfectly ...