Hypochondroplasia

Hypochondroplasia is a developmental disorder caused by an autosomal dominant genetic defect in the fibroblast growth factor receptor 3 gene, FGFR3. It produces disproportionately short stature, short limbs and a head that looks large in comparison with the underdeveloped parts of the body, and it is classified as a form of short-limbed dwarfism. Affected people appear normal at birth, but as the infant grows the arms and legs fail to develop properly and the body becomes thicker and shorter than usual. Some twenty different FGFR3 mutations have been linked to the condition. Diagnosis rests on the physical features, X-rays and genetic testing. Treatment is usually orthopedic surgery and physical therapy, with genetic counseling advised; there is no cure, and life expectancy is normal, with adult height of about 132 to 147 centimetres.