Several genome-wide association studies (GWASs) have recently reported the associations of fat mass and the obesity-associated (FTO) gene with obesity, breast cancer and diabetes.61,62 FTO has been associated with the DNA damage response, DNA repair and inflammatory mechanisms.2 It encodes a protein that functions as a nucleic acid demethylase, targeting N6-methyladenosine (m6A) modifications on RNA. This evidence concerns the gene FTO and breast cancer.