As dysfunctional complex I is the most frequent biochemical feature of mitochondrial disease (41, 42) and is broadly implicated in the pathogenesis of cancer, diabetes, parkinsonism, and aging (43, 44, 45), this study highlights DNAJC30 as a target within the complex I repair pathway with potential therapeutic implications far beyond the optic neuropathies. This evidence concerns the gene DNAJC30 and diabetes mellitus.