OPA1 and autosomal dominant optic atrophy: Autosomal dominant optic atrophy (DOA, OMIM 605290) is the most commonly diagnosed inherited optic neuropathy, and, in a recent epidemiological study, the minimum prevalence was estimated at 1 in 25 000 in the North of the United Kingdom (Figure 1).46 The majority of families with DOA (∼ 60%) harbour pathogenic mutations in OPA1 (3q28-q29), which codes for a dynamin-related GTPase protein located within the inner mitochondrial membrane.47, 48 It is a ubiquitous protein and abundant levels have been detected in RGCs, the inner ear, and the brain.