WFS1 and diabetes mellitus: Mutations in the WFS1 gene are generally associated with optic atrophy as part of the autosomal recessive Wolfram syndrome phenotype (DIDMOAD, diabetes insipidus, diabetes mellitus, optic atrophy, deafness)[91,92] or with autosomal dominant progressive low-frequency sensori-neural hearing loss that can be associated with DOA, with or without impaired glucose regulation[93,94], supporting the notion that mutations in WFS1 as well as in OPA1 may lead to optic atrophy combined with hearing impairment.