Any primary mitochondrial disease in which the cause of the disease is monoallelic or biallelic variants in the OPA1 gene. While optic atrophy is present in most affected cases, OPA1 is a mitochondrial protein and thus features of this disease include abnormal mitochondrial morphology and multiple mitochondrial DNA deletions, and can affect other organ systems and. Extraocular features can include progressive sensorineural hearing impairment, cognitive impairment, peripheral neuropathy, myopathy, ragged-red muscle fibers, and exercise-induced lactic acidemia, while additional ocular features can include progressive visual loss, central scotoma, and color vision abnormalities. [ https://clinicalgenome.org/working-groups/clinical-domain/inborn-errors-of-metabolism/ https://clinicalgenome.org/working-groups/clinical-domain/ocular-cdwg/ ]