FGFR3 and hypochondroplasia: As the main role of the FGFR3 is the regulation of cell proliferation in epiphyseal plate chondrocytes, many FGFR3 mutations are characterized by short-limbed bone dysplasia of varying severity (hypochondroplasia, achondroplasia, thanatophoric dysplasia); craniosynostosis is rare in the first two of these disorders.