RESUMO
OBJECTIVE: To screen for genetic mutations in 35 patients with Leber's hereditary optic neuropathy (LHON). METHODS: Polymerase chain reaction and DNA sequencing were used to screen for the presence of mitochondrial DNA mutations. RESULTS: The total detection rate of top 3 common LHON mutations were 20.0%, which included 6 cases of ND4 11778 G to A, 1 case of ND1 3460 G to A. No ND6 14484 T to C mutation was detected. A ND4 G11719A synonymous mutation was found in all patients. In addition, 21 other mutations were discovered among 23 patients, among which 13 had a single mutation, 8 had a second mutations, and 2 had a third mutation. Among the 21 mutations, ND4 11778 G to A had a frequency of 28.6%(6/21). ND1 3552 T to A, ND6 14470 T to C, ND4 11794 T to C, ND1 3497 C to T and 3644 T to C respectively had a frequency of 19.0% (4/21), 19.0%(4/21), 14.3%(3/21), 9.5%(2/21) and 9.5%(2/21). Among the 3 patients who harbored a ND4 11794 T to C mutation, 2 were heteroplasmic and one was homoplasmic in nature. CONCLUSION: The ND4 11778 G to A mutation is common in the Top "3" primary mutations of patients with LHON. Candidate LHON mutation ND1 3552 T to A or ND1 3644 T to C resulted in LHON pathogenesis as single or synergistic effect. The visual impairment at onset of the disease with candidate mutation were better than the eyes with the ND4 11778 G to A mutation.
