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All About Cell-Free Fetal DNA Testing

For the newly pregnant mother, there’s no greater source of anxiety than not knowing whether the baby you are carrying is truly healthy. We all hope for a complication free pregnancy, but fear of genetic disorders or other birth defects are always quite prevalent. Birth defects, as well as genetic abnormalities are all real concerns, and while few babies are actually born with such defects, that doesn’t lower the anxiety level for an expecting mother.

The only way to truly know – outside of waiting for the baby to be born – is to have the doctor order these non-invasive prenatal tests. While there is no way to test for all birth defects, there are tests in place that have a greater than 95-percent success rate in testing for common genetic abnormalities such as trisomy 21 (Down Syndrome), trisomy 18 (Edward Syndrome) and trisomy 13 (Patau Syndrome). There’s no greater anxiety reliever in the first trimester than getting the call that your healthcare provider has received the results and that everything is normal. That’s not to say that a baby with genetic or other birth defects will be any less loved, but planning and preparation make living with these conditions much easier.


The problem with this is that – until a few years ago – there were no great options for prenatal DNA testing that weren’t invasive. We now have tests without the traditional risks of invasive tests and all they involve is a drop of blood from the expectant mother.

Both doctors and patients alike have been calling for a more complete lineup of noninvasive tests for expectant mothers. In fact, companies such as Sequenom Inc, have lead the way to make these tests most accessible to modern healthcare professionals. For the last few decades, the only option to test for common genetic abnormalities was using methods that were invasive in nature to both mother and child. With technology, came cell-free DNA tests, which only require a drop of blood, can be done as early as 10 weeks, and deliver the results directly to your healthcare provider within 5 days from the time the lab receives the sample. The test is said to be able to predict with greater than 99-percent accuracy all cases of trisomy 21 (Down Syndrome), 98-percent of all trisomy 18 (Edward Syndrome) pregnancies and 65-percent of all trisomy 13 (Patau Syndrome) pregnancies.

The test itself actually sequences DNA in order to look for common abnormalities within the trisomies. For example, trisomy 21 (Down Syndrome), is a relatively common (about 1 in 1,000 births) genetic abnormality that is easily spotted during DNA testing due to the extra set of chromosomes it produces. The average human is born with 46 chromosomes, while trisomy 21 cases have an extra set, for a total of 47 chromosomes.

If something was found in the panel, it’s often necessary to do additional testing. Amniocentesis and Chronic Villus Sampling (CVS) tests are often the next step, but they’re not entirely necessary in most cases. Your doctor will be able to tell you for sure as to whether additional tests are worth taking.

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