IRX3 and obesity due to melanocortin 4 receptor deficiency: The interaction of the FTO gene SNPs with the Iroquois homeobox 3 (IRX3) and Iroquois homeobox 5 (IRX5), genes also associated with the development of obesity and an effector of the FTO variants (48), may jointly regulate adipogenesis and cause white adipose tissue browning in mice (49).