From studies on humans and model animals, it appears that the genes implicated in the monogenic type of obesity may also carry mutations that stand out from the polygenic background (LEP, PCSK1, LEPR, POMC, MC4R, SIM1, NTRK2, BDNF, SH2B1, MRAP2, KSR2, ADCY3). This evidence concerns the gene LEP and obesity due to melanocortin 4 receptor deficiency.