OPA1 and autosomal dominant progressive external ophthalmoplegia: Dominant Optic Atrophy (DOA) constitutes one of the most common inherited optic neuropathies and pathogenic OPA1 variants have been identified in ~ 60% of these families [19] whilst pathogenic variants in TWNK clinically manifests as autosomal dominant progressive external ophthalmoplegia (adPEO) [20].