The proband of 12 ARCA families and 37 sporadic SCA patients, previously excluded for the FRDA, SCA1, SCA2, SCA3, SCA6, SCA7, SCA8, SCA10, SCA12, SCA17 and DRPLA mutations, were analysed for this novel SETX mutation. The gene discussed is ATN1; the disease is autosomal dominant cerebellar ataxia.