OPA1 and optic atrophy: However, no further mutations were identified in a cohort of 48 patients with nonsyndromic optic atrophy (in whom mutations in optic atrophy 1 gene [OPA1] and the most frequent LHON mutations [mitochondrial DNA {mtDNA} G11778A, G3460A, T14484C, and G15257] had been excluded) [4].