RARS2 and cerebellar ataxia: A mitochondrial cause of ataxia was detected in ten patients including six patients with homozygous mutations in POLG, siblings with m.8561C > G [16], a patient with a single deletion in mtDNA and a patient with compound heterozygous mutations in RARS2. Recently, the m.8561C > T mutation has been reported in a patient with severe mitochondrial disorder [22] suggesting that MT-ATP genes may be mutational hotspots in the aetiology of ataxia.