FTO and obesity due to melanocortin 4 receptor deficiency: Other genes associated with obesity include MC4R (synergistic with FTO); the leptin gene and receptor, and genes encoding ectoenzyme nucleotide pyrophosphate phosphodiesterase 1, tumor necrosis factor alpha, interleukin-6, peroxisome proliferator–activated receptor gamma, angiotensin-converting enzyme, and glutathione S-transferase11.