ERF and acanthosis nigricans: These include mutations in FGFR2 explaining Apert, Crouzon, Pfeiffer, and Jackson-Weiss syndromes; mutations in FGFR3 leading to Muenke syndrome and acanthosis nigricans, in TWIST1, causing Saethre-Chotzen syndrome; mutations in JAG1 leading to Alagille syndrome, ERF, TCF12 causing ERF-related and TCF12-related craniosynostosis, and other mutations associated with Mendelian forms of syndromic craniosynostosis (64, 80–82).