What we do know is that FTO is most highly expressed in the brain, where the sensing of amino acids can influence the activity of pathways controlling food intake. We would hypothesize that subtle effects of the risk alleles on expression of FTO in key brain regions, such as the hypothalamus, are likely to influence the way in which these cells sense amino acid levels. As we discuss above, there is evidence that human carriers of the susceptible SNPs in FTO not only consume more food, but also show an alteration in nutrient preference, perhaps suggesting that FTO status can influence the central sensing of dietary macronutrient composition. Thus the role of FTO in amino acid sensing may provide some clues towards understanding the cellular basis for this physiological phenomenon.
