The fat mass and obesityassociated protein (FTO) is an Fe(II)and 2-oxoglutarate (2OG)-dependent oxygenase that catalyzes the oxidationof N-methyl groups in nucleic acids, and, in particular,of N6-methyladenosine (m6A)in RNA.1−3 FTO is a potential medicinal chemistry target dueto its roles in obesity and cancer. This evidence concerns the gene FTO and obesity due to melanocortin 4 receptor deficiency.