MC4R and obesity due to melanocortin 4 receptor deficiency: AAV-Cre-mediated deletion of PVNMC4R leads to hyperphagia and obesity (Garza et al., 2008), while PVN-specific MC4R re-expression markedly suppresses hyperphagia and body weight gain in obese MC4R-null (MC4RloxTB/loxTB) mice (Shah et al., 2014).