Common clinical features include ptosis, external ophthalmoplegia, proximal myopathy and exercise intolerance, cardiomyopathy, sensorineural deafness, optic atrophy, pigmentary retinopathy, encephalopathy, seizures, stroke-like episodes, ataxia, spasticity and lactic acidosis.

Leigh syndrome is an early-onset progressive neurodegenerative disorder characterized by the presence of focal, bilateral lesions in one or more areas of the central nervous system including the brainstem, thalamus, basal ganglia, cerebellum and spinal cord.

Clinical features depend on which areas of the central nervous system are involved and include subacute onset of psychomotor retardation, hypotonia, ataxia, weakness, vision loss, eye movement abnormalities, seizures, dysphagia and lactic acidosis.

[8] One case report of a pathogenic mutation in NDUFS8 found that it resulted in complex I mitochondrial deficiency and a diagnosis of Leigh syndrome.

The patient’s symptoms included apnea, cyanosis, hypercarbia, hypotonia, brisk tendon reflexes, ankle clonus, and erratic seizures.