FTO was the first m6A demethylase to be identified, showing high demethylation activity against m6A, which can affect metabolic diseases and the development of obesity in humans, while ALKBH5 can catalyze the removal of m6A modifications from nuclear RNA (mainly mRNA), which in turn can affect nuclear RNA export, metabolism and gene expression, and even fertility in mice (Zheng et al., 2013; Huang et al., 2020; Prakash et al., 2021). Here, FTO is linked to obesity due to melanocortin 4 receptor deficiency.