POMC and obesity due to melanocortin 4 receptor deficiency: Recently, we showed that mice with a targeted mutation in the pro-opiomelanocortin (Pomc) gene [Pomctm1/tm1 mice; C57BL/6J mice genetically modified so that they are unable to synthesize desacetyl-α-MSH and α-MSH] are hyperphagic and develop obesity when fed a regular chow diet (8).