METTL3 and obesity due to melanocortin 4 receptor deficiency: Participating in this mechanism are “writer” methyltransferases, such as methyltransferase-like 3 (METTL3) and Wilms tumor 1-associated protein (WTAP), and “eraser” demethylases, such as AlkB homolog H5 (ALKBH5) and fat mass and obesity (FTO).