The potential functional link between FTO and IRX3 is supported by evidence from murine, human, and in vitro studies showing that the IRX3 promoter strongly interacts with the obesity-associated interval within FTO, and that obesity-linked SNPs are associated with IRX3 but not with FTO expression [10, 11]. The gene discussed is FTO; the disease is obesity due to melanocortin 4 receptor deficiency.