What are the genetic changes related to hypochondroplasia ?
About 70 percent of all cases of hypochondroplasia are caused by mutations in the FGFR3 gene. This gene provides instructions for making a protein that is involved in the development and maintenance of bone and brain tissue. Although it remains unclear how FGFR3 mutations lead to the features of hypochondroplasia, researchers believe that these genetic changes cause the protein to be overly active. The overactive FGFR3 protein likely interferes with skeletal development and leads to the disturbances in bone growth that are characteristic of this disorder.  In the absence of a mutation in the FGFR3 gene, the cause of hypochondroplasia is unknown. Researchers suspect that mutations in other genes are involved, although these genes have not been identified.