Additionally, as has been demonstrated, obesity traits may also be associated with polymorphisms in genes related to the ECS, i.e., CNR1, CNR2, NAPE-PLD (N-acyl phosphatidylethanolamine phospholipase D), FAAH1 (fatty acid amide hydrolase 1), FAAH2 (fatty acid amide hydrolase 2), and MGL (monoglyceride lipase). This evidence concerns the gene CNR1 and obesity due to melanocortin 4 receptor deficiency.