DNA or deoxyribonucleic acid is the genetic material that is located in the cell nucleus and mitochondria. It provides key genetic information about an individual, and also helps in establishing parentage. DNA testing can be carried out either during pregnancy or after birth. There can be several reasons behind performing DNA testing during pregnancy.
Reasons for Prenatal DNA Test
It can be required to clear any doubt regarding the identity of the father of the child. It may become essential to establish paternity to provide a proof for paternity suit. It would in turn, help the mother to get financial support for the child. A father may also ask for a proof before taking up his parental duties and responsibilities.
In addition to this, prenatal DNA testing can help determine the gender of the child, as well as to screen the fetus' genome for any chromosomal or genetic aberrations. it can be used to screen the DNA for a wide range of genetic mutations (hereditary/spontaneous), that may result in the development of any type of a disease, disorder, or a syndrome.
It is widely used to screen for abnormalities in the fetus in cases where either or both the parents have a family history of a certain health problem. For example, this test can help to determine whether the fetus will suffer from problems like downs syndrome, thalassemia, hemophilia, etc.
Procedures for Prenatal DNA Testing
DNA testing performed during pregnancy is known as prenatal DNA testing, but if carried out after birth, it is called postnatal DNA testing. In prenatal DNA testing, a sample of tissues from the placenta or a sample of amniotic fluid (the fluid in which the embryo remains suspended) is collected to be examined and analyzed.
The invasive methods used for collecting these samples involve several health related risks for both mother and the fetus. There are basically two types of prenatal testing, amniocentesis and Chorionic Villus Sampling.
This procedure can be performed within 14 to 24 weeks of pregnancy. In this method, a special needle is inserted into the uterus through the abdomen to collect amniotic fluid. Ultrasound is used to facilitate the process by guiding the needle.
However, amniocentesis may involve several serious health risks including leakage of the amniotic fluid, injury to fetus, and miscarriage.
Chorionic Villus Sampling
This test can be executed within 10 to 13 weeks of pregnancy. Here, a needle or small tube is inserted into the uterus thorough the vagina and cervix in order to extract a sample of chorionic villi.
Chorionic villi is a small piece of fingerlike tissue that is found on the uterine wall. This tissue is produced from the same fertilized egg and therefore can be used to get important genetic information about the fetus.
The methods and procedures employed for this procedure carry several serious risks for the unborn child and the mother. If pregnancy has progressed past the 24th week, then these risks become so significant that the physicians usually do not suggest such tests.
It is true that establishment of parental identity is of crucial importance in certain circumstances, but postnatal DNA testing can also serve this purpose. It is also advisable to weigh the various risk associated with the process.
Sometimes, it may become inevitable, especially in case of hereditary diseases and abnormalities. A physician should always be consulted to know about these tests in detail and how to avoid the risks associated with them.