Among RAI1 target genes are Bdnf (brain-derived neurotrophic factor) and Htr2c (serotonin receptor 2c) (Huang et al., 2016; Burns et al., 2010), both of which are implicated in hyperphagia leading to obesity, a phenotype accompanying SMS, concomitant with altered locomotor activity (Huang et al., 2016; Burns et al., 2010; Kernie et al., 2000; Nonogaki et al., 2003). Here, RAI1 is linked to obesity due to melanocortin 4 receptor deficiency.