FGFR1 and Crouzon syndrome: Moreover, mutations in FGFR1 and FGFR2 genes have been established in the pathogenesis of some syndromes in which clefts are present, such as Apert syndrome (FGFR2), Crouzon syndrome (FGFR2, FGFR3), Hartsfield syndrome (FGFR1) and Kallmann syndrome (FGFR1, FGF8) [18].