As the result of the CRC-SCA natural history study, we found that the rates of disease progression of SCA1, SCA2, SCA3, and SCA6 (annual increase in SARA by 1.61, 0.71, 0.65, and 0.87 points, respectively) (12) are consistent with those in EUROSCA (15). This evidence concerns the gene ATXN1 and autosomal dominant cerebellar ataxia.