OPA1 and cerebellar ataxia: Up to 20% of OPA1-mutated patients also develop additional more complex neurodegenerative disorder with extra-ocular manifestations, including deafness [1], chronic progressive external ophthalmoplegia, ptosis, ataxia, peripheral neuropathy and mitochondrial myopathy with multiple mtDNA deletions, leading to a syndromic disease sub-group known as ‘ADOA plus’ (OMIM#125250) [2, 3].