MSTN and obesity due to melanocortin 4 receptor deficiency: Other genetic associations related to chronic diseases noted in this population include the apolipoprotein E gene polymorphisms, the myostatin gene in abdominal obesity and obesity [41], the AMDI variant in homocysteine metabolism that predisposes children to obesity [42], and the PPAR-gamma polymorphisms contributing to nonalcoholic fatty liver disease [43].