FGFR3 and achondroplasia: Different mutations in the fibroblast growth factor receptor 3 (FGFR3) gene have been linked to ACH (p.gly375cys and p.gly380arg) (references within and reviewed in 5,6), but most de novo ACH cases (97%) are caused by a transition mutation (c.1138G>A) associated with the p.gly380arg amino acid change in the protein's transmembrane domain (7,8).