PPP2R2B and spinocerebellar ataxia type 12: We tested this idea by attempting to generate isogenic iPSC lines with different lengths of the CAG repeat in exon 7 of human PPP2R2B gene (Fig. 1A), part of our long term goal of generating cell models of spinocerebellar ataxia type 12 (SCA12), a disorder caused by expanded CAG repeats at this locus17,18.