MC3R and obesity due to melanocortin 4 receptor deficiency: Recently, a case of homozygous loss‐of function of MC3R was reported in humans, with this patient displaying obesity, increased fat mass, reduced lean mass and a delayed puberty phenotype such as those previously characterized in MC3R KO mice (Lam et al., 2021), suggesting that the function of MC3R may be conserved across species.