In contrast to the relatively rare incidence of CATSHL syndrome caused by FGFR3 inactivation, activating mutations in FGFR3 that result in achondroplasia (31) and hypochondroplasia (32) occur at an estimated frequency between 1/15,000 and 1/40,000 live births. The gene discussed is FGFR3; the disease is achondroplasia.