FGFR2 and Crouzon disease: In addition, other craniosynostosis syndromes, including Jackson-Weiss syndrome and Crouzon syndrome, are also caused by gain-of-function mutations in the D2-D3 linker region of FGFR1 or FGFR2 in a ligand-dependent or independent manner (Moosa and Wollnik, 2016).