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 CACNA1A and autosomal dominant cerebellar ataxia.