Saturday, November 22, 2014
These types of tests are most commonly performed on expectant mothers that are deemed as increased risk pregnancies, such as a mother that is over 35, or has had a previous family history of genetic birth defects. In this case, it wasn't at all uncommon for a physician to recommend an amniocentesis in order to test the baby for common genetic abnormalities. Amniocentesis is still used, but now it is just one of multiple options that your healthcare provider has in order to test for chromosomal abnormalities.
Amniocentesis is an invasive procedure, but until recently it was the only way to test for certain chromosome abnormalities, genetic disorders, or neural tube defects. Trisomy 21 (Down Syndrome) is the most common of these abnormalities but the test can also uncover additional chromosomal abnormalities such as those found in trisomy 18 (Edward Syndrome) or trisomy 13 (Patau Syndrome). Besides the uncomfortable nature of the procedure, another drawback with amniocentesis is that the family would typically have to wait until the fifteenth week of the pregnancy, and it isn’t unheard of to wait until twenty weeks to be able to do a safe amniocentesis. The obvious benefit to the prenatal DNA testing is both in speed (from lab to your healthcare provider's office in 5 days) and the fact that the tests are simple and more accessible than ever.
With an obvious need for noninvasive prenatal tests, doctors have begun using cell free DNA tests that can detect the some of the same sort of genetic issues as a traditional amniocentesis. Bioscience companies like Sequenom are making this sort of testing easily accessible by medical professionals who prefer a test without the risk of prenatal invasive procedures. It seems the problem in past years wasn't the procedural awareness - DNA sequencing and genetic testing has been around for more than a decade - but dealing with off-site laboratories that made this sort of testing accessible.
A simple prick from a needle and a small amount of blood now give lab technicians all they need in order to test for genetic mutation and deformities such as trisomy 21 (Down Syndrome), trisomy 18 (Edward syndrome) and trisomy 13 (Pateau Syndrome). In fact, the testing has success rates of 99-percent at detecting trisomy 21 pregnancies, 98-percent with trisomy 18, and about 65-percent with trisomy 13. With trisomy 13 tests, there is often a need for an amniocentesis or chronic villus sampling (CVS) with positive test results.
The test itself often relies on a simple blood test taken from the mother. A small amount of blood is drawn and sent to a laboratory and your healthcare provider will receive the results within 5 days from the date the laboratory received the initial sample.
The future is bright for early detection of all types of birth defects. These simple noninvasive procedures are set to revolutionize the way doctors test for complication in high risk pregnancies. In many cases, knowing about defects before the birth of the child helps the parents to prepare for the specific set of challenges they'll face after the baby is born.
This is a blog post by Nancy Evans.
Posted by MedFriendly at 3:20 PM