In the clinic, FTO-associated overgrowth is reminiscent of the Beckwith-Wiedemann syndrome (BWS), which leads to overgrowth and IR, which also implicates both IGF2 and H19, and which is imperfectly modeled by any single mouse model64: BWS is a human genomic imprinting disorder at a locus harboring IGF2 and H19, that is characterized by overgrowth and early onset obesity65, although BWS is often an underestimated cause of syndromic obesity. This evidence concerns the gene H19 and obesity due to melanocortin 4 receptor deficiency.