On this basis, two of the clusters were associated with an adverse impact on β-cell function, three were characterized by insulin sensitivity (differing with respect to their relationship to obesity, fat distribution, and lipid metabolism), and a sixth cluster [designated only in the Mahajan et al. (20) paper] had less clearcut phenotypic features (20, 38) (Table 2). This evidence concerns the gene INS and obesity due to melanocortin 4 receptor deficiency.