FTO and obesity due to melanocortin 4 receptor deficiency: Many follow-up studies in children and adults from different populations, including European, African, and Asian ancestries, have confirmed the initial findings on FTO.105–109 Most studies are focused on the rs9939609 FTO single nucleotide polymorphism (SNP) that shows the strongest association with BMI in Caucasians; but more recently the variant SNP rs3751812 has been proposed to capture the FTO association with obesity in both European and African ancestry,109,110 even though it may not be the optimal tag-SNP for populations of European ancestry.