| A rare mitochondrial oxidative phosphorylation disorder with a variable clinical phenotype. Manifestations include infantile onset of epileptic encephalopathy, hypotonia, global developmental delay, failure to thrive, complex movement disorder and liver involvement along with childhood onset of severe myoclonus epilepsy, cognitive decline, progressive hearing and visual impairment and progressive tetraparesis. Serum lactate may be increased and brain imaging shows variable atrophy and white matter abnormalities. |