Progressive mitochondrial disease resulting from a novel missense mutation in the mitochondrial DNA ND3 gene

We describe a 42-year-old man who presented with a progressive history of epilepsy, stroke-like episodes, bilateral optic atrophy, and cognitive decline. Investigation of his muscle biopsy revealed a specific defect in complex I activity. Subsequent analysis of the mitochondria genome identified a novel heteroplasmic T10191C mutation in the ND3 gene. The mutation was present at Lower levels in blood from the patient and unaffected maternal relatives and is the first pathogenic mitochondria DNA mutation in the ND3 gene to be described.