FTO and obesity due to melanocortin 4 receptor deficiency: RNAs can be methylated by Methyltransferase-like 3(METTL3), Methyltransferase-like 14 (METTL14) (“writers”), and demethylated by the fat mass- and obesity-associated (FTO) protein and the α-ketoglutarate-dependent dioxygenase alkB homolog 5 (ALKBH5) protein (“erasers”) [36].