FTO and obesity due to melanocortin 4 receptor deficiency: For instance, despite the relatively large effect of the FTO SNPs on BMI with 0.35 kg/m2 per allele or 1 kg for a person who is 1.7 m tall reported in 2007 [27], it took until 2014 to explain the regulatory circuitry and mechanistic chains behind the associations between FTO variants and obesity.