Definition:

Leigh syndrome is a severe neurological disorder, characterized by bilaterally symmetrical necrotic lesions in the basal ganglia and brainstem. Most frequently the central nervous system is affected, with psychomotor retardation, seizures, nystagmus, optic atrophy, ataxia, or respiratory failure. Some patients also present with peripheral nervous system involvement or non-neurologic abnormalities. In the majority of cases, dysfunction of the mitochondrial respiratory chain complex or of the pyruvate dehydrogenase complex are responsible for the disease. Patterns of inheritance include X-linked recessive, autosomal recessive, and mitochondrial.