Obesity-associated variants within FTO form long-range functional connections with IRX3

Genome-wide association studies in diverse populations have reproducibly associated variants within introns of FTO with increased risk for obesity and type-2 diabetes.While the molecular mechanisms linking these noncoding variants with obesity are not immediately obvious, subsequent studies in mice demonstrated that FTO expression levels influence body mass and composition phenotypes. Yet, no direct connection between the obesity-associated intronic variants and FTO expression or function has been made. We show that the obesity-associated noncoding sequences within FTO are functionally connected, at megabase distances, primarily with the homeobox gene IRX3, rather than with FTO. 4C-seq samples for Fto/fto and Irx3/irx3a genes promoters in different samples: adult mouse brain, E9.5 mouse embryos and 24hpf zebrafish embryos.