Hypochondroplasia (HCH) is a developmental disorder caused by an autosomal dominant genetic defect in the fibroblast growth factor receptor 3 gene (FGFR3) that results in a disproportionately short stature, micromelia[3] and a head that appears large in comparison with the underdeveloped portions of the body. It is classified as short-limbed dwarfism.[2][4]
Individuals affected by this disorder appear normal at birth. As the infant grows, however, their arms and legs do not develop properly, and their body becomes thicker and shorter than normal.[3] The following are characteristics consistent with this condition:[1]
Hypochondroplasia is inherited as an autosomal dominant trait affecting the FGFR3 gene on chromosome 4p16.3. There is currently no cure for this condition.[2]
Hypochondroplasia can be caused by point mutations such as p.Lys650Asn.[6][3] In FGFR3, some 20 different mutations have been associated with hypochondroplasia,[7] and it seems to have a role in skeletal dysplasia.[8]
The diagnosis of this condition can be done via X-rays (with lack of normal distance L1toL5),[9] and additionally genetic testing is available to ascertain hypochondroplasia.[10] However, the physical characteristics are one of the most important in determining the condition.[3]
^ abcdefgBober, Michael B.; Bellus, Gary A.; Nikkel, Sarah M.; Tiller, George E. (1 January 1993). "Hypochondroplasia". GeneReviews. PMID20301650. Retrieved 18 December 2016.update 2013
