POLG and hereditary ataxia: Common recessive causes were p.Trp748Ser in POLG and the recently discovered intronic expansion in RFC1. SCA3, FRDA and SPG7-related ataxia have been reported to be the most common hereditary ataxias among Europeans [4, 20], but we found only two patients with FRDA and none with SCA3 or mutations in SPG7. Altogether, 34% of our patients received a genetic diagnosis and the three most common genetic causes accounted for half of the diagnoses.