MDM2 and Intellectual disability: Where CDKN2A produces two major proteins p16(INK4), which is a cyclin-depnednet kinase inhibitor, and p14(ARF), which binds the p53-stabilizing protein MDM2 (Serrano et al., 2000); PHIP is associated with Chung-Jansen syndrome, featuring behavioral problems, intellectual disability, obesity, and dysmorphia (Webster et al., 2016; Jansen et al., 2018); and LEP encodes leptin, a protein that plays a critical role in the regulation of body weight.