One of the most accepted hypotheses to explain the molecular mechanism takes into consideration that the expression regulation of FTO and other nearby genes (RPGRIP1L and IRX3) is a process controlled by an obesity‐associated region in intron 1 of FTO, which we also replicated in this study (Ronkainen et al., 2015; Smemo et al., 2014; Stratigopoulos et al., 2014). This evidence concerns the gene IRX3 and obesity due to melanocortin 4 receptor deficiency.