INS and obesity due to melanocortin 4 receptor deficiency: The findings by Masuo et al. and by others [10]–[15] are in line with previous hypothesis of a putative causal effect of uric acid on adiposity which states that uric acid could mediate obesity and other features of the metabolic syndrome by reducing endothelial nitric oxide and decreasing insulin-mediated glucose uptake in skeletal muscle [8].