As illustrated in figure 4, we found significant correlations between SARA (reflecting ataxia severity) and CSA at all vertebral levels for SCA1 (r=−0.61 to −0.62; online supplemental table S14), SCA2 (r=−0.41 to −0.61; online supplemental table S14) and SCA3 (r=−0.42 to −0.52; online supplemental table S14). This evidence concerns the gene ATXN2 and cerebellar ataxia.