OPA1 and mitochondrial disease: Thus, facing a multisystemic mitochondrial syndrome with optic atrophy it is important to check for OPA1 mutations, but many other mitochondrial diseases not related to OPA1 can also display a clinical presentation similar to DOAplus, as recently evidenced by the discovery of a singular mis-sense mutation in the MFN2 gene leading to a DOAplus phenotype[98].