METTL3 and obesity due to melanocortin 4 receptor deficiency: The m6A modification is dynamic and reversible in mammalian cells, which could be installed by methyltransferases (writers) consisting of METTL3 (methyltransferase-like 3), METTL14, WTAP (Wilms tumor 1-associated protein), KIAA1429, RBM15 (RNA-binding motif protein 15), and its paralog (RBM15B), whereas its removal is regulated by demethylases (erasers) such as FTO (fat mass and obesity-associated) and ALKBH5 (ALKB homolog 5).