Purpose: To study the clinical features of Leber's hereditary optic neuropathy (LHON) in Thai patients as compared with patients in the United States, Europe, and other Asian countries.
Methods: The blood mitochondrial DNA of patients from 19 Thai pedigree families was studied for LHON mutation by restriction enzyme analysis.
Results: Mitochondrial mutation at nucleotide position 11778 was detected in 37 affected patients and 21 unaffected maternal relatives. Ten of the 19 families were sporadic in transmission. The male preponderance in affected patients was 76%. The onset of visual loss ranged from 6 to 53 years of age (mean = 21.5 years). Of the 31 patients whose eyes were affected bilaterally, 48.4% developed visual loss simultaneously. Unilateral visual loss was found in 2 patients but 1 already had a blind eye resulting from trauma. Onset interval between eyes was up to 12 months (mean = 2.3 months). No associated heart disease or neurological disorder was detected in our pedigrees. Hyperemic disc, retinal telangiectasia, and tortuosity of vessels appeared on ophthalmoscopy in 29% of the patients. Final visual outcome was 0.1, or worse in 82.3%, with a mean follow-up period of 19.5 months.
Conclusion: The clinical features of LHON in Thai patients are similar to those found in patients harboring the 11778 mutation in the United States, Europe, and Japan. However, although there is a male predominance in all populations studied, this is not so marked in the European and Thai populations.