OPA1 and cerebellar ataxia: Over the next nearly ten years, no biallelic mutations were described in OPA1 patients, but in 2010 two distinct mutations in OPA1 were found in two siblings showing optic atrophy and deafness without neurological symptoms, and in the same report, compound heterozygous mutations were identified in two adult siblings presenting with optic atrophy, ataxia, myopathy, neuropathy, and spasticity.