The pro-inflammatory state of obesity inhibits insulin receptor substrate 1 (IRS-1) signaling pathways in adipose and muscle tissue, as well as limits the activity of peroxisome proliferator-activated receptor gamma (PPARγ), which is responsible for the processes of fat storage and lipid synthesis in adipose tissue [37]. The gene discussed is IRS1; the disease is obesity due to melanocortin 4 receptor deficiency.