ATXN3 and multiple system atrophy: An association was found between MSA and CAG repeat sizes in ATXN2 but not CAG repeat size in ATXN1 or ATXN3, implying that ATXN2 may play a role as a risk factor for MSA (at least) in the Chinese population; however, no modifying effects of repeat lengths at SCA1, SCA2 or SCA3/MJD loci on AO of MSA were observed, possibly due to sample size.