The replicated T2DM risk loci fall into three categories (Table S1): (i) those that impact the T2DM risk through impaired β-cell function (ALX4, BCL11A, CDKAL1, CDKN2A/B, GCK, HNF1A, HNF1B, HNF4A, IGF2BP2, JAZF1, KCNJ11, KCNQ1, SLC30A8, TCF7L2, WFS1); (ii) those that act through modulating insulin action (ADAMTS9, DUSP9, PPARγ); and (iii) those that were primarily associated with BMI, obesity and adiposity but subsequently identified also as affecting T2DM risk through insulin action (FTO, GNPDA2, MC4R, TFAP2B). The gene discussed is ALX4; the disease is obesity due to melanocortin 4 receptor deficiency.