If the cis-acting element is changed from T to C, AACATF (rsl421085) cannot bind to ARID5B, and no inhibitory effect of ARID5B is elicited, leading to the upregulation of IRX3 by more than two-fold, thereby inhibiting the expression of UCP1, reducing basal metabolic rate, and promoting the onset of obesity. This evidence concerns the gene IRX3 and obesity due to melanocortin 4 receptor deficiency.