POLG and recessive mitochondrial ataxia syndrome: The most common syndromic mitochondrial diseases presenting with cerebellar ataxia as a cardinal sign include: (i) Kearns-Sayre syndrome; (ii) NARP (neuropathy, ataxia and retinitis pigmentosa) syndrome; (iii) POLG gene spectrum disorders, highlighting the mitochondrial recessive ataxia syndrome (MIRAS), including SANDO (sensory ataxic neuropathy, dysarthria and ophthalmoplegia) and Mitochondrial Spinocerebellar ataxia with epilepsy syndrome (MSCAE); (iv) MELAS syndrome (mitochondrial encephalopathy, lactic acidosis and stroke-like episodes); and (v) primary coenzyme Q10 deficiency [4–7].