LEP and obesity due to melanocortin 4 receptor deficiency: These include loss of function mutations in genes which encode for components along the leptin‐melanocortin pathway such as leptin (LEP), leptin receptor (LEPR), melanocortin 4 receptor (MC4R), proconvertase 1 (PCSK1) and proopiomelanocortin (POMC), resulting in severe, early‐onset and penetrant obesity.20, 21, 22, 23