POP1 and obesity due to melanocortin 4 receptor deficiency: Specifically, lower expression of Pum2, Polr1d, Notch4, Tcf7l2, Tcf12, Psmc3, and Zfhx3 correlates with increased body fat percentage, fat mass, body weight, and total mass in the mouse, which is comparable to knockdown of the orthologs puf-8, fbf-2, rpac-19, glp-1, pop-1, hlh-2, rpt-5, and zfh-2 causing obesity in C. elegans.