ATXN1 and spinocerebellar ataxia type 1: Examining data from a published study of somatic expandability in post-mortem brain tissue of SCA1 and MJD patients [55], we found that the repeat-length normalised levels of somatic expandability in SCA1 were approximately double the levels found in MJD in both cerebral cortex (NMJD = 11; NSCA1 = 7; Mann-Whitney U = 0; P<0.0001) and cerebral white matter (NMJD = 9; NSCA1 = 6; Mann-Whitney U = 0; P<0.001); similar to the relative levels of germ line expandability observed in these disorders (Figure 2A and Table S1) [31].