[Analysis of mutations and heteroplasmy at mitochondrial DNA 11778 using non-RI single strand conformation polymorphisms in Leber's hereditary optic neuropathy].

Leber's hereditary optic neuropathy(LHON) is a maternally inherited mitochondrial disease of an acute or subacute bilateral loss of central vision. G to A substitutions at nucleotide position 11778 in mitochondrial DNA(mt DNA) have been identified in approximately 40% to 90% of patients. In this study, regions containing mt DNA 11778 mutations were analyzed by polymerase chain reaction(PCR), non-RI single strand conformation polymorphisms(SSCP) and direct sequencing. In 26 visually affected patients, mt DNA 11778 mutations were detected in 9 patients (36.4%). In one pedigree of a LHON patient(L-6), four unaffected family members had heteroplasmy of the 11778 mutation using non-RI SSCP. Ratios of the heteroplasmy between wild type and mutant mt DNAs can be detected in non-RI SSCP and accurately quantified by video densitometric analyzer. Two types of novel polymorphisms, 11696 G to A and 11719 A to G, in the mt DNA region were also found in this non-RI SSCP analysis. Non-RI SSCP is an efficient and accurate method for diagnosis of mt DNA 11778 mutations and quantifying heteroplasmy in patients with LHON and pedigrees.