The receptor for leptin, an obesity-associated adipokine that was significantly elevated in our obese patient group (Table 1), has also been shown to crosstalk with IGF-1R, resulting in greater IGF-1R activation and an upregulation of Akt and ERK1/2 phosphorylation [49]. The gene discussed is MAPK3; the disease is obesity due to melanocortin 4 receptor deficiency.