LEP and obesity due to melanocortin 4 receptor deficiency: The huge review performed by Paracchini et al23 in 2005 regarding the 3 polymorphisms in the LEPR gene (K109R, Q223R, K656N) and the 2 polymorphisms in the PPARG gene (C161T and P12A) in healthy and obese subjects suggested no evidence of an association between the genes involved in leptin regulation and obesity.