OPA1 and cerebellar ataxia: Since 2011, a new, early-onset OPA1-related syndromic entity, distinct from those previously described, has been reported in some patients with a severe neurological syndrome associating early-onset optic neuropathy with spinocerebellar degeneration, pyramidal signs, peripheral neuropathy, gastrointestinal dysmobility and retarded development, a phenotype fully compatible with the Behr syndrome (MIM# 210000) [24–27].