Thus, the regulation of m6A-RNA methylation by the WMM complex as well as FTO may be involved in pathogenesis of human obesity or T2D, although further studies are needed to identify the main target of m6A-RNA methylation by the WMM complex and to elucidate how different genes are regulated by both m6A-RNA methylation and demethylation to understand the mechanism of subsequent cell cycle regulation and adipocyte differentiation and maturation. Here, FTO is linked to obesity due to melanocortin 4 receptor deficiency.