Hypochondroplasia

Hypochondroplasia
Hypochondroplasia is autosomal dominant in inheritance.
Specialty	Medical genetics
Symptoms	Skeletal dysplasia[1]
Causes	FGFR3 gene mutation[2]
Diagnostic method	Physical finding, X-ray[3]
Treatment	Special education, Laminectomy [1]

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]

Signs and symptoms[]

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]

• Brachydactyly
• Short stature
• Micromelia
• Skeletal dysplasia
• Abnormality of femur

Cause[]

Hypochondroplasia is transmitted as an autosomal dominant trait affecting the FGFR3 gene on chromosome 4p16.3. There is currently no cure for this condition.^[2]

Pathophysiology[]

TYK

This disorder results from mutations in the proximal tyrosine kinase domain of the FGFR3 gene.^[3] This gene plays an important role in embryonic development, playing a part in regulating activities such as cell division, migration and differentiation.^{[medical citation needed]}

Hypochondroplasia can result from p. Lys650Asn as well.^[5][3] In FGFR3, some 20 different mutations have been associated to hypochondroplasia,^[6] and it seems to have a role in skeletal dysplasia.^[7]

Diagnosis[]

The diagnosis of this condition can be done via X-rays (with lack of normal distance L1 to L5),^[8] and additionally genetic testing is available to ascertain hypochondroplasia.^[9] However, the physical characteristics are one of the most important in determining the condition.^[3]

Treatment[]

Spinal stenosis

Treatment of hypochondroplasia usually takes the form of orthopedic surgery and physical therapy. Genetic counseling is advised for individuals and their families. Specifically in the case of spinal stenosis, one option is laminectomy.^[3][1]

Prognosis[]

Life expectancy for individuals with hypochondroplasia is normal; height is about 132–147 centimetres (4 ft 4 in–4 ft 10 in).^[10]

See also[]

• Achondroplasia
• List of congenital disorders

References[]

Further reading[]

• editors, Sally Radovick, Margaret H. MacGillivray; MacGillivray, Margaret H. (2010). Pediatric Endocrinology a Practical Clinical Guide, Second Edition (2nd ed.). Dordrecht: Springer. ISBN 9781607613954. Retrieved 21 December 2016.CS1 maint: extra text: authors list (link)
• Kelly, Evelyn B. (2013). Encyclopedia of human genetics and disease. Santa Barbara, Calif.: Greenwood. ISBN 9780313387142. Retrieved 21 December 2016.

External links[]

Scholia has a topic profile for Hypochondroplasia.