MC4R and major depressive disorder: Regarding the interaction of MC4R gene and HDP on depression (Fig. 3), logical inverse relationships were observed between CT genotype and HDP on depression in both crude and adjusted models (OR: -0.56, 95% CI: -3.69-2.57, P: 0.72) (OR: -4.17, 95% CI: -9.28-0.94, P: 0.11), although this interaction was not statistically significant in both models.