IFNG and obesity due to melanocortin 4 receptor deficiency: Obesity is associated with an increased incidence of cancer and infections (78–80), which may, at least in part, be due to NK cell dysfunction, since NK cells in the peripheral blood of obese humans (both adults and children) exhibit reduced cell frequencies, diminished cytotoxicity, and impaired IFN-γ production (35, 81, 82).