Posts made in March, 2016


What’s cffDNA?

Cell free fetal DNA testing, or shortly cffDNA is a new test that gives parents’ the ability to know whether their unborn baby suffers from certain chromosome disorders. Such disorders include Down Syndrome, Patau Syndrome, and Edwards Syndrome. Besides these, any other condition connected to irregular chromosome numbers can be detected. Of course, other tests in the past existed and still exist, such as amniocentesis, which give accurate results. However, one of the most positive aspects of cffDNA is the non-invasive method of examination which is done through the mother’s blood. The material which is examined is the cffDNA. This is the genetic material that is released by the placenta into the bloodstream of the mother. The release of cffDNA starts in the initial trimester of the pregnancy. At the beginning of the pregnancy, it is released in low quantities, but it increases as the pregnancy progresses. It serves to detect the genetic map of the baby that is developing.

Screening/Diagnostic Testing

This test represents a screening test, rather than a diagnostic test. It is not standard in use as the older routine prenatal tests, but it can be requested. This test gives more accurate, specific and sensitive data. In cases when the screening findings appear abnormal, the direction of the procedure turns to more invasive methods such as CVS (chorionic villus sampling) and amniocentesis. Only after the latter two are performed, a correct diagnosis can be carried out.

As stated, cell free DNA testing can be ordered, but usually under certain circumstances. These may include cases when the mother has an increased possibility of carrying a child that has increased risk of a chromosome disorder because of maternal age, previous pregnancy with a trisomy, known circumstances that place the fetus at risk, as well as several other related factors.

After the test has been performed and the protein examined, the results can be positive or negative. If the cffDNA results are negative, then it means that the circumstances for the baby having a trisomy 21, 18 or 13 are highly unlikely. However, other types of chromosome abnormalities that have not been tested should not be excluded just yet. If the test results are positive then the fetus is at increased risk. As mentioned, this is only a screening test. After receiving positive results, then it is obligatory to perform the diagnostic tests to be certain.

Additional information about the DNA test

The cffDNA test is still new and being worked on, so it may take a while until it becomes routine clinical use. As the research expands, so do the possibilities of usage of the test. Some of the flaws of the test are the false negative results which a mother can get if the test was performed before the tenth week of the pregnancy. This can happen because of the scarcity of the protein in the woman’s bloodstream. Test results can also be affected by obesity, which in turn decreases the amount of the cffDNA in blood. Researchers have also found a rare instance where different cell lines with genetic information can appear in the placenta. That means that some cells can contain a trisomy, while others don’t, thus giving a false prediction about the overall pregnancy in general.

What are your thoughts on the reliability of cffDNA testing?

 

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