Free Fetal DNA Testing

When a couple is expecting a child, they wonder what gender it is and what defects it could possibly have. In the past, the best method to answer these question was a procedure called amniocentesis. Amniocentesis is a technique where a needle is inserted into a women’s amniotic sac through her abdomen in order to collect amniotic fluid which could then be analyzed. This process gives results with a high degree of certainty, however it has some flaws. Since a long needle is being injected into the womb, there is the risk that it could poke something that it is not supposed to. Therefore, there is miscarriage in about 1% of amniocentesis patients. That being said, there is now a new method of determining the genetic information of the fetus, and it is much less invasive. The new test goes by the name of free fetal DNA testing, and all the mother has to do is get blood taken. By collecting the blood of the mother, companies like Harmony can separate out the fetal DNA and examine it to find birth defects and determine the gender, to a lesser degree of certainty than amniocentesis. The blood of the fetus and the mother do not directly mix, however, the placenta sheds tissue into the mother’s blood stream daily. Because of the placental shedding, fetal DNA can find itself leaking into the mother’s blood stream and mixing in with her blood and loose DNA. Once the scientists collect the blood sample of the mother, they then need to separate the fetal DNA from the mother’s DNA. Scientists have discovered that the fetal DNA fragments are much smaller than the mother’s DNA fragments. Using this knowledge, they use electrophoresis in order to separate the DNA fragments. In electrophoresis, the molecules are dragged through a gel matrix using an electric current causing the DNA fragments to arrange themselves by size. Once the fetal DNA fragments have been identified, they can then be used to determine things about the genetics of the fetus.