OPA1-mutant DOA (OPA1, MIM #165500) is primarily characterized by early onset retinal ganglion cell degeneration and up to 20% of patients will also present with additional symptoms (DOA+), including deafness, ataxia, peripheral neuropathy and a worsened visual prognosis in comparison to pure DOA [234]. Here, OPA1 is linked to cerebellar ataxia.