FGFR3 and hypochondroplasia: Furthermore, equivalent substitutions in FGFR3 (p.(Asn540Lys), p.(Asn540Thr) and p.(Asn540Ser)) are known to result in gain of function and to cause hypochondroplasia (MIM 146000), an autosomal dominant skeletal dysplasia characterized by disproportionate short stature (Webster and Donoghue 1997; Deutz-Terlouw et al. 1998; Mortier et al. 2000; Thauvin-Robinet et al. 2003).