FGFR1 and Pfeiffer syndrome: Occasionally, a specific mutation in FGFR1, p.Pro252Arg can cause Pfeiffer syndrome—phenotypically these families have classic hand and foot anomalies with variable presence of craniosynostosis and generally milder craniofacial features [Muenke et al., 1994; Rossi et al., 2003; Hackett and Rowe, 2006].