Schinzel-Giedion syndrome is a severe condition that is apparent at birth and affects many body systems. Signs and symptoms of this condition include distinctive facial features, neurological problems, and organ and bone abnormalities. Because of the READ MORE

Schizoaffective disorder is a mental health condition that includes features of both schizophrenia and a mood disorder such as bipolar disorder or depression. The prefix "schizo-" refers to the psychotic symptoms of schizophrenia that affect a person READ MORE

Schizophrenia is a disorder of the brain that affects a person's thoughts, perceptions, and behavior. Affected individuals may have difficulty distinguishing between what is real and what is not (psychosis). Schizophrenia is typically diagnosed durin READ MORE

Schwannomatosis is a disorder characterized by multiple noncancerous (benign) tumors called schwannomas, which are a type of tumor that grows on nerves. Schwannomas develop when Schwann cells, which are specialized cells that normally form an insulat READ MORE

Schwartz-Jampel syndrome is a rare condition characterized by permanent muscle stiffness (myotonia) and bone abnormalities known as chondrodysplasia. The signs and symptoms of this condition become apparent sometime after birth, usually in early chil READ MORE

SCN8A -related epilepsy with encephalopathy is a condition characterized by recurrent seizures (epilepsy), abnormal brain function (encephalopathy), and intellectual disability. The signs and symptoms of this condition typically begin in infancy. The READ MORE

Seasonal affective disorder is a mental health condition that is triggered by the changing of the seasons. This condition is a subtype of major depressive disorder and bipolar disorder. Major depressive disorder is characterized by prolonged sadness READ MORE

Senior-Løken syndrome is a rare disorder characterized by the combination of two specific features: a kidney condition called nephronophthisis and an eye condition known as Leber congenital amaurosis. Nephronophthisis causes fluid-filled cysts to dev READ MORE

Sepiapterin reductase deficiency is a condition characterized by movement problems, most often a pattern of involuntary, sustained muscle contractions known as dystonia. Other movement problems can include muscle stiffness (spasticity), tremors, prob READ MORE

Septo-optic dysplasia is a disorder that affects early brain development. This condition is typically defined as a combination of at least two of the following three features: underdevelopment (hypoplasia) of the nerves that carry visual information READ MORE

SETBP1 haploinsufficiency disorder is a condition that involves speech and language problems, intellectual disability, and distinctive facial features. In people with SETBP1 haploinsufficiency disorder, problems with vocabulary and the production of READ MORE

Severe congenital neutropenia is a condition that increases the risk of repeated infections in affected individuals. People with this condition have an abnormally low level (deficiency) of neutrophils, a type of white blood cell that plays a role in READ MORE