Baby gender DNA test: the science behind it.
Knowing the gender of an unborn baby has been possible for a while now. Ultrasound is a technique widely available and used by millions of pregnant woman each year, at least in the Occidental world. Although typically associated with gender prediction, the ultrasound is actually employed to monitor several aspects of fetal development, being sex prediction just a “side advantage”. Many parents-to-be were happy to be able to know the sex of their babies by week 20th when the ultrasound was introduced. Now, however, people in reproductive age are used to this and many want to known even sooner.
DNA to the rescue
As with ultrasound, techniques designed to study fetal genetic material with diagnostic purposes were also co-opted for gender determination. These techniques aim to obtain a sample of the fetal DNA to test for risks of some genetic anomalies such as Down Syndrome. Corionic Villus Sampling (CVS) is usually performed between weeks ten and twelve of pregnancy. For CVS, a small sample of the “hairs” or projections (or chorionic villi) that are part of the placenta is taken through the abdominal wall or cervix with a catheter while guided by ultrasound. If the transcervical technique can not be used, as it happens when the woman has a genital infection such as gonorrhea or herpes, or has a chronic inflammation of cervix, then the transabdominal method is used. Although very small, there is a risk of damage or miscarriage, and therefore this procedure is indicated only when suspicion about genetic disorders are raised. Gender prediction can be done through CVS since the sex can easily be established by simple DNA testing. However, few people would go through the hassle, cost and risks of a CVS only to know the gender of the baby.
Breaking the barriers
Until just two years ago the placenta was thought to be the only source of fetal DNA available for these kind of studies, but scientists unexpectedly found out that small numbers of fetal cells pass through the placental barrier and make their way into the mother’s bloodstream. The fetal DNA can be detected from week 6 after conception. What does this mean for gender prediction? Cells carry DNA, and DNA, even in minute amounts can be revealed by the sensitive and powerful technique known as PCR (for Polymerase Chain Reaction). In theory, one could design a PCR experiment to reveal the presence of DNA from Y-chromosome in the mother’s blood. A positive result would indicate that the baby is a boy, and a negative, a girl. Now, from theory to practice. Does this really work? A team of Italian geneticists carried out a comprehensive study in which they tested blood from about 1,600 pregnant women. The predictions made by these tests were confronted later when the babies were born, and the rate of success was overwhelming: 99% of correct predictions. Even higher than the trusted ultrasound.
Even though gender prediction is one of the most obvious applications, this technique will prove to be very valuable to develop new and more effective ways to diagnose fetal anomalies at early stages without the risks associated with CVS and other invasive procedures. As per baby sex, some laboratories have already launched gender prediction tests that can be done very easily at home with a drop of a mom’s finger as soon as she reached week 6th., with absolutely no risks and high accuracy.
Source: GeneDNATest