PNPLA2 and obesity due to melanocortin 4 receptor deficiency: Products of some genes play a role in the body’s energy metabolism, including, in particular, lipid metabolism: the apolipoprotein A5 gene (ApoA5), the fat mass and obesity-associated gene (FTO), the fatty acid-binding protein 2 gene (FABP2), the adipose triglyceride lipase gene (ATGL), the adiponectin gene (ADIPOQ), the adiponectin receptor gene (ADIPOR2), and others [23].