To confirm that someone has achondroplasia and not a different genetic cause for their short stature and health issues there are a few different types of tests:
Testing
Before birth
If there are some findings on the ultrasound or sonogram that makes the doctor think about achondroplasia, depending on how far along in the pregnancy the woman is, they may suggest a special genetic testing on a sample of amniotic fluid. This testing would be collected through an amniocentesis which is an invasive test. That would require planning to make sure the correct test was done because there are several testing options from panels like the prenatal skeletal dysplasia testing panel at http://www.genedx.com/test-catalog/disorders/achondroplasia-ach/ or reading through the FGFR3 in a sequencing test.
Of course, if there is a unknown change in the FGFR3 gene resulting in achondroplasia in the family, they can just test for that gene change.
After birth
A diagnosis of achondroplasia is usually made not through genetic testing but by physical examination and review of X-rays. There is a very specific set of criteria looking at health issues, symptoms, and measurements that doctors use to determine if a person has achondroplasia.
Genetic testing can confirm a diagnosis of achondroplasia, but is not required for the diagnosis. This is done by obtaining a sample of DNA from a person, typically through a blood draw. The sample is first tested for the two most common changes in the FGFR3 gene that are associated with achondroplasia. One of these two changes is present in about 99% of people with a clinical diagnosis of achondroplasia. Genetic laboratories can also look at the entire FGFR3 gene (gene sequencing) to detect much more rare genetic changes. This approach may be beneficial when it is unclear whether a diagnosis of hypochondroplasia or achondroplasia is more appropriate. There are several labs that do this type of testing and there is a list on the Genetests site.
There is also the option of a genetic testing panel that tests for achondroplasia AND other causes of dwarfism. A good example of that is the [link url=" http://geneticslab.emory.edu/tests/MM171″ target=”_blank”>Disproportionate Short Stature: Sequencing Panel at EGL Genetics. Of course, if there is a unknown change in the FGFR3 gene resulting in achondroplasia in the family, they can just test for that gene change.
Regular Checkups
If someone has achondroplasia there are important things to check on a regular basis. Generally for newly diagnosed child, it is recommended that they have:
Other Questions About Achondroplasia
- Who else in my family should I test for achondroplasia?
- Where do I find other people with achondroplasia?
- What types of tests should be done for achondroplasia?
- What type of delivery is recommended for pregnant mothers with achondroplasia?
- What treatments are available for sleep apnea in patients with achondroplasia?
