Most of the patients with mutations in genes related to mitodynamics presented a neurological phenotype; our MSTO1‐mutant subjects have indeed a myopathy associated with cerebellar ataxia, underlined by hypotrophy of the cerebellar vermis; the sisters A1 and A2 also present a multisystem condition with developmental delay, particularly motor impairment with ataxia and dysmorphisms. Here, MSTO1 is linked to cerebellar ataxia.