IRX3 and obesity due to melanocortin 4 receptor deficiency: In total, 19 obese patients and 9 lean subjects (2.21% vs. 0.98%) had rare nonsynonymous IRX3 variants (P = 0.038; OR = 2.27; 95% CI, 1.02–5.05) (Fig. 4B), indicating that rare nonsynonymous variants of IRX3 were associated with the development of human obesity.