Dwarf; Dwarfism; Achondroplastic dwarfism
Achondroplasia is a disorder of bone growth that causes the most common type of dwarfism.
Achondroplasia is one of a group of conditions called chondrodystrophies or osteochondrodysplasias. These rare genetic disorders cause problems with the development of bone, cartilage, and connective tissue.
Achondroplasia is caused by a change (mutation) in the fibroblast growth factor receptor 3 (FGFR3) gene. This prevents bone growth and mainly affects the long bones in the arms and legs. People with achondroplasia have a short stature, with an average height under 4 feet 6 inches (137 centimeters).
Achondroplasia may be inherited as an autosomal dominant trait. This means that if a child gets the defective gene from one parent, the child will have the disorder. If one parent has achondroplasia, the infant has a 50% chance of inheriting the disorder. If both parents have the condition, the infant's chances of being affected increase to 75%.
However, most cases (about 80%) appear as spontaneous mutations. This means that two parents without achondroplasia may give birth to a baby with the condition.
Achondroplastic dwarfism results in the following:
Almost all people with achondroplasia have normal intelligence and will have a normal lifespan. Children with the disorder may develop at a slower rate than other children the same age.
During pregnancy, a prenatal ultrasound may show excessive amniotic fluid surrounding the unborn infant.
Examination of the infant after birth shows increased front-to-back head size. X-rays of the long bones can reveal achondroplasia in the newborn.
CT scan or MRI of the brain may be done if there are signs of hydrocephalus ("water on the brain").
Neuroimaging is needed to check the base of the head to look for signs of spinal cord compression.
Sleep studies help detect problems with sleep apnea.
Children with achondroplasia will need ongoing monitoring as they grow to check for health problems that can develop.
There is no specific treatment for achondroplasia. The disorder may cause certain health conditions, which need to be treated when they cause problems.
Vosoritide (Voxzogo) is a new medicine approved for use in children age 5 years and older who are still growing. This once daily injection may slightly improve bone growth.
Children and adults will need adaptations to their home, school, and work environment to accommodate a shorter stature.
Being physically different from others can be difficult for children who may be made fun of or bullied. Even in adulthood, people with dwarfism may be stared at or treated differently. Connecting with others affected by the disorder can help children and their families feel less alone.
More information and support for people with achondroplasia and their families can be found at:
People with achondroplasia seldom reach 5 feet (1.5 meters) in height. Intelligence is in the normal range. Infants who receive the abnormal gene from both parents do not often live beyond a few months.
People with achondroplasia should have regular checkups throughout their life, as the condition can cause other health problems. Most problems can be treated.
Complications that may develop include:
If there is a family history of achondroplasia and you plan to have children, you may find it helpful to speak to your health care provider.
Genetic counseling may be helpful for prospective parents when one or both have achondroplasia. However, because achondroplasia most often develops spontaneously, prevention is not always possible.
Genetic and Rare Diseases Information center website. Achondroplasia. rarediseases.info.nih.gov/diseases/8173/achondroplasia. Updated November 8, 2021. Accessed April 7, 2022.
Hoover-Fong JE, Horton WA, Hecht JT. Disorders involving transmembrane receptors. In: Kliegman RM, St Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM, eds. Nelson Textbook of Pediatrics. 21st ed. Philadelphia, PA: Elsevier; 2020:chap 716.
Krakow D. FGFR3 disorders: thanatophoric dysplasia, achondroplasia, and hypochondroplasia. In: Copel JA, D'Alton ME, Feltovich H, et al, eds. Obstetric Imaging: Fetal Diagnosis and Care. 2nd ed. Philadelphia, PA: Elsevier; 2018:chap 50.
Legare JM. Achondroplasia. 1998 Oct 12 [Updated 2022 Jan 6]. In: Adam MP, Ardinger HH, Pagon RA, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2022. www.ncbi.nlm.nih.gov/books/NBK1152/.
National Organization for Rare Disorders website. Achondroplasia. rarediseases.org/rare-diseases/achondroplasia/. Accessed April 7, 2022.BACK TO TOP
Review Date: 12/12/2021
Reviewed By: Neil K. Kaneshiro, MD, MHA, Clinical Professor of Pediatrics, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
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