These include CDKAL1, CDKN2A, and CDKN2B that influence β-cell mass; MTNR1B, TCF7L2, and KCNJ11 that influence β-cell function; FTO that is associated with obesity; and IRS1 and PPAR-γ that contribute to insulin resistance independent of obesity.14 Furthermore, there may be unique markers of genetic susceptibility to DM2 in certain ethnic groups with a high incidence of DM2,15,16 and interactions between individual genetic variants may also influence DM risk. Here, IRS1 is linked to obesity due to melanocortin 4 receptor deficiency.