Mice carrying two additional gain-of-function Fgfr2 mutations that can be found in humans with Crouzon syndrome – Fgfr2C342Y/+ (Cys342Tyr) (Eswarakumar et al., 2004) and Fgfr2W290R/+ – have phenotypes that recapitulate the clinical characteristics of this syndrome (Park et al., 1995a). Here, FGFR2 is linked to Crouzon syndrome.