Achondroplasia Outline
Alosha Kuznetsov
5/30/2013

Definition : Achondroplasia - is a common cause of dwarfism. It occurs as a sporadic mutation in approximately 75% of cases (associated with advanced paternal age) or may be inherited as an autosomal dominant genetic disorder.
People with achondroplasia have short stature, with an average adult height of 131 centimeters (51.5 inches) (4 ft 3.5 in) for males and 123 centimeters (48.4 inches) (4 ft 0.4 in) for females. Achondroplastic adults are known to be as short as 62.8 cm (24.7 inches) [2 ft 0.7 in]. The disorder itself is caused by a change in the DNA for fibroblast growth factor receptor 3 (FGFR3), which causes an abnormality of cartilage formation. If both parents of a child have achondroplasia, and both parents pass on the mutant gene, then it is very unlikely that the homozygous child will live past a few months of its life. The prevalence is approximately 1 in 25,000.
Symptoms : People who have achondroplasia have abnormal bone growth that causes the following clinical symptoms: short stature with disproportionately short arms and legs, short fingers, a large head (macrocephaly) and specific facial features with a prominent forehead (frontal bossing) and mid-face hypoplasia.The intelligence and life span in individuals with achondroplasia is usually normal. Infants born with achondroplasia typically have weak muscle tone (hypotonia). Because of the hypotonia, there may be delays in walking and other motor skills. Compression of the spinal cord and/or upper airway obstruction increases the risk of death in infancy. People with achondroplasia commonly have breathing problems in which breathing stops or slows down for short periods (apnea). Other health issues include obesity and recurrent ear infections. Adults with achondroplasia may develop a pronounced and permanent sway of the lower back (lordosis) and bowed legs. The problems with the lower back can cause back pain leading to difficulty with walking.

Diagnosis : Achondroplasia is diagnosed by characteristic clinical and X-ray findings in most affected individuals. In individuals who may be too young to make a diagnosis with certainty or in individuals who do not have the typical symptoms, genetic testing can be used to identify a mutation in the FGFR3 gene. Genetic testing can identify mutations in 99 percent of individuals who have achondroplasia. Testing for the FGFR3 gene mutation is available in clinical laboratories.
Treatment : No specific treatment is available for achondroplasia. Children born with achondroplasia need to have their height, weight and head circumference monitored using special growth curves standardized for achondroplasia. Measures to avoid obesity at an early age are recommended. A magnetic resonance imaging (MRI) or CT scan may be needed