FAAH and obesity due to melanocortin 4 receptor deficiency: 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).