To generate SCA-iPSCs and control iPSCs, peripheral blood mononuclear cells (PBMCs) or dermal fibroblasts, obtained from four patients with SCA2 or SCA3, and three normal individuals, were transduced with Sendai or retro viruses, encoding OCT4, SOX2, KLF4 and c-MYC (OSKM) (Table S1). Here, ATXN3 is linked to autosomal dominant cerebellar ataxia.