GWAS studies have implicated SNPs close to VPS13C, C2CD4A, and C2CD4B in altered T2D susceptibility. We tested the association between genotype at one of the previously identified SNPs rs4502156 and the likely causal SNP rs7163757 (61, 66) (r2 = 0.939, D′ = 0.979 with rs4502156) and VPS13C expression in human islet samples from 53 donors. Initial analysis for rs4502156 and rs7163757 including all samples showed no significant association. Interaction plots indicated a possible interaction between sex and genotype, which was tested by including the interaction term in the ANCOVA model (see materials and methods). This was found to be significant (P = 0.015, n = 53), so data were stratified by sex, and subsequently males and females were analyzed separately (Fig. 1, A–C). Analysis of females revealed a significant association between possession of the risk allele (C) at rs7163757 and lowered VPS13C expression (P = 0.041, n = 40; Fig. 1C). A similar sex interaction (P = 0.016, n = 53) was also observed for rs4502156, and likewise a significant association was detected between genotype at this locus and expression of VPS13C in females (P = 0.043, n = 40). An association was also detected between rs4502156 (not shown), as well as rs7163757 (P = 0.011, n = 40; Fig. 1, D–F), with C2CD4A mRNA levels in female donors but not with C2CD4B (Fig. 1, G–I). Subsequent functional studies in the present report focussed upon VPS13C.