Relative frequency of SCA1 (68 %) was assessed considering the number of SCA1 pedigrees (138 probands) versus the overall number of molecularly confirmed ADCA pedigrees: 138 SCA1, 23 SCA2 1 SCA3, 38 SCA8 and 3 SCA17 (203 probands/families). Here, ATXN1 is linked to autosomal dominant cerebellar ataxia.