Leigh syndrome is the most frequent, although genetically heterogeneous, mitochondrial disease. Leigh syndrome is a typical example of how mitochondrial disorders present and how mitochondrial diagnostics is carried out. It is a progressive, subcortical encephalopathy.

The first symptoms usually appear before two years of age and consist of optic atrophy, ophtalmoparesis, hypotonia, ataxia, and dystonia. Neuropathy and myopathy are common and the specific neurological features help to distinguish Leigh syndrome from other brain diseases, such as encephalitis. The course is fluctuating, with exacerbations often triggered by mild intercurrent illnesses. Most patients die a few years after the onset of symptoms.

Etiology

 mutations in the SDHA gene coding for the subunit A of succinate dehydrogenase complex (MIM.600857)
 SURF1 mutations (patients with hypertrichosis) (#16222681#)