Achondroplasia is a disorder of bone growth that causes the most common type of dwarfism.
Achondroplasia is one of a group of disorders called chondrodystrophies, or osteochondrodysplasias.
Achondroplasia may be inherited as an autosomal dominant trait, which means that if a child gets the defective gene from 1 parent, the child will have the disorder. If 1 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 appear as spontaneous mutations. This means that 2 parents without achondroplasia may give birth to a baby with the condition.
The typical appearance of achondroplastic dwarfism can be seen at birth. Symptoms may include:
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. There may be signs of hydrocephalus ("water on the brain").
X-rays of the long bones can reveal achondroplasia in the newborn.
There is no specific treatment for achondroplasia. Related abnormalities, including spinal stenosis and spinal cord compression, should be treated when they cause problems.
People with achondroplasia seldom reach 5 feet 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.
Health problems 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 1 or both have achondroplasia. However, because achondroplasia most often develops spontaneously, prevention is not always possible.
Carson BS, Groves M, Yassari R. Neurologic problems of the spine in achondroplasia. In: Quiñones-Hinojosa A, ed. Schmidek and Sweet's Operative Neurosurgical Techniques. 6th ed. Philadelphia, PA: Elsevier Saunders; 2012:chap 184.
Horton WA, Hecht JT. Disorders involving transmembrane receptors. In: Kliegman RM, Stanton BF, St. Geme JW III, Schor NF, eds. Nelson Textbook of Pediatrics. 20th ed. Philadelphia, PA: Elsevier; 2016:chap 696.BACK TO TOP
Review Date: 11/19/2015
Reviewed By: Neil K. Kaneshiro, MD, MHA, Clinical Assistant Professor of Pediatrics, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.
The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- 2016 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.