METTL3 and obesity due to melanocortin 4 receptor deficiency: The abundance and functions of m6A in RNA are governed by the interplay between its “writers” (methyltransferases, such as methyltransferase like 3 (METTL3) and METTL14); “erasers” (demethylases, such as fat mass- and obesity-associated protein) and “readers” (binding proteins, mainly including YT521-B homology domain family members (YTHDFs)) [18].