RAB5B and obesity due to melanocortin 4 receptor deficiency: Therefore, we tested whether the GDR measured by euglycemic hyperinsulinemic clamp, circulating testosterone measured by LC-MS/MS, or adipocyte size was associated with (1) genes with largest fold changes CD74, CYP1B1 and GPT; (2) candidate genes identified in GWAS studies of PCOS (RAB5B), T2D (PPARG, SVEP1 and BCKDHA), and obesity (RTN4); and, (3) a gene overlapping with methylation (DMAP1).