All probands with OPA1 mutations had clinical symptoms and signs of DOA (Table 4). The disease occurred insidiously in most probands, with reduced visual acuity noticed at about 12 years old (12+-9.5 years; ranging between 2 and 35 years). The mean age for the probands' first visit to the eye clinic was about 15 years (15+-8.8 years; ranging from 4 to 35 years). Interestingly, two probands (le1574 and le1601) experienced significant visual deterioration after taking antituberculosis medicine. Additional segregation analysis of the mutations was performed in two sporadic cases, i.e., le1432 and le2062, through contact tracing of the OPA1-positive probands (Figure 2). The two patients had no siblings, but their parents were available for further analysis. All four parents were farmers and were visually asymptomatic by self-report. However, the father of le1432 and the mother of le2062 harbored an OPA1 mutation. Ophthalmic examination of the two "healthy carriers" demonstrated mild phenotype of optic atrophy: mild reduced visual acuity, attenuated retinal vessels, temporal disc pallor, and thinning RNFL on the OCT scan (Table 4).