Juvenile Leigh Syndrome, Optic Atrophy, Ataxia, Dystonia, and Epilepsy due to T14487C Mutation in the mtDNA-ND6 Gene: A Mitochondrial Syndrome Presenting From Birth to Adolescence

An increasing number of reports describe mutations in mitochondrial DNA coding regions, especially in mitochondrial DNA-encoded nicotinamide adenine dinucleotide dehydrogenase subunit genes of the respiratory chain complex I, as causing early-onset Leigh syndrome. The authors report the molecular findings in a 24-year-old patient with juvenile-onset Leigh syndrome presenting with optic atrophy, ataxia dystonia, and epilepsy. A brain magnetic resonance imaging revealed bilateral basal ganglia and thalamic hypointensities, and a magnetic resonance spectroscopy revealed an increased lactate peak. The authors identified a T14487C change causing M63V substitution in the mitochondrial ND6 gene. The mutation was heteroplasmic in muscle and blood samples, with different mutation loads, and was absent in the patient's mother's urine and blood samples. They suggest that the T14487C mtDNA mutation should be analyzed in Leigh syndrome, presenting with optic atrophy, ataxia, dystonia, and epilepsy, regardless of age.