Interestingly, Erol et al., trying to investigate whether there is a correlation between OPG and insulin resistance in children with obesity, found that OPG levels were lower in such children, but failed to detect a difference in OPG concentrations between children with both obesity and NAFLD compared to those with obesity without NAFLD (51). The gene discussed is TNFRSF11B; the disease is obesity due to melanocortin 4 receptor deficiency.