DDX3X and syndromic intellectual disability: For instance, DDX3X (Dead Box Helicase 3, X-Linked), KDM6A/UTX (Lysine Demethylase 6A/UTX), MAGEC3 (Melanoma Antigen Gene Family, Member C3), CNKSR2 (Connector Enhancer of Kinase Suppressor of Ras 2), KDM5C (Lysine Demethylase 5C), ATRX (Alpha Thalassemia/Intellectual Disability Syndrome X-Linked) are tumor suppressor X-linked genes located in the non-pseudoautosomal region (PAR) which has been reported to escape silencing by XCI and thus contribute to cancer sex bias (Dunford et al., 2017).