al., 2012)] in chr4p12 GABAA RNA expression compared to fibroblast genomic DNA in 7 of 16 lines (44%). In contrast, 0 of 11 lines (0%) heterozygous for an exonic SNP in the AKR1C3 gene (chr10p15) showed an imbalance in expression of the two alleles (Fisher’s exact test, p=0.02). Of the lines that were heterozygous at two or more chr4p12 GABAA genes, 6 of 8 lines displayed concordant allelic expression across markers (i.e., either a greater than ±0.5ΔCT difference for each gene marker or no bias for each gene). Both of the lines that were discordant over the interval displayed allelic bias in 3 of 4 GABAA genes, but with the most distal gene (GABRG1 in one line, GABRB1 in the other line) showing less than a 0.5ΔCT difference. In the case of donor 727 (rs279858*T/T genotype), neural cells differentiated from two independent iPSC clones (727-6 and 727-8) had allelic bias for opposite chromosomes over this region (Figure 6). This is consistent with a random, mitotically-stable clonal event occurring at the time of iPSC generation producing complementary allelic bias in the chr4p12 GABAA genomic interval for the 2 independent iPSC lines from this subject.
