METTL3 and obesity due to melanocortin 4 receptor deficiency: m6A modification is mediated and facilitated by methylases such as METTL3 (methyltransferase-like 3), METTL14, and WTAP (Wilms’ tumor 1-associated protein), whereas modification can be reversed by demethylases such as FTO (fat mass and obesity-associated protein) and ALKBH5 (alkylation repair homolog 5) (35).