Clinical phenotype and the G11778A mutation of mitochondrial DNA in patients with Leber’s hereditary optic neuropathy in Taiwan

Abstract

We report the clinical manifestations and mitochondrial DNA (mtDNA) mutations of nine Chinese patients with Leber’s hereditary optic neuropathy from seven families in Taiwan. The nine probands were all males, aged 19 to 43 years at the time of the study and with ages of onset ranging between 13 and 30 years. They were characterized by an acute or subacute onset of visual loss in one eye, which progressed to the other eye within a few weeks. Their visual outcome was poor, although improvement was noted in four patients. A muscle biopsy from one patient showed a decreased activity of cytochrome c oxidase and subsarcolemmal mitochondrial aggregation. All patients and unaffected maternal family members had a homoplasmic G11778A mtDNA mutation regardless of variations in clinical manifestation. High frequencies of environmental factors such as smoking, alcohol consumption, trauma, and/or military training were found in these patients. We conclude that even though a homoplasmic G11778A mtDNA mutation was found in all patients and their maternal family members, this mutation could not account for the presentation of the clinical features. Additional genetic, epigenetic, and/or environmental factors may be important trigger factors in the clinical expression.