Different activating mutations in the FGFR3 gene may cause achondroplasia (OMIM 100800), thanatophoric dysplasia type I (OMIM 187600), which is a short-limb dwarfism syndrome usually lethal in the perinatal period, as well as hypochondroplasia (OMIM 146000) with clinical features, including short-limbed dwarfism, lumbar lordosis, short and broad bones, and caudal narrowing of interpediculate distance of lumbar spine. The gene discussed is FGFR3; the disease is achondroplasia.