Exclusive homoplasmic 11778 mutation in mitochondrial DNA of Chinese patients with Leber's hereditary optic neuropathy.

PURPOSE To investigate the degree of heteroplasmy of the 11778 mtDNA mutation in Chinese patients with Leber's hereditary optic neuropathy (LHON). METHODS Seventeen Chinese Leber's pedigrees, including 24 patients, 17 unaffected maternal lineages, 4 internal controls, and 6 unrelated controls, were screened for the 11778 mtDNA mutation. This was carried out by analysis of the restriction fragment length polymorphism, single-strand conformation polymorphism, and DNA sequencing. RESULTS All patients and unaffected maternal lineages, regardless of their symptoms, had homoplastic 11778 mtDNA mutation, which was revealed by restriction fragment length polymorphism analysis and single-strand conformation polymorphism analysis. CONCLUSION Exclusive homoplasmy of the 11778 mtDNA mutation in Chinese LHON patients was found in this study. Homoplasmy of the 11778 mtDNA mutation cannot account for the variation in the clinical phenotype of Chinese Leber's patients.