Nowadays, it is possible to obtain information about the health of the baby before birth, to take precautions against diseases and problems that may occur after birth, and even to receive medical treatments during pregnancy. In this case, especially recently, the importance of prenatal genetic diagnosis test, called prenatal diagnosis test, has emerged. Assoc. Prof. from the Department of Gynecology and Obstetrics and In Vitro Fertilization Center. Dr. Ali Emre Tahaoğlu answered the frequently asked questions about prenatal diagnosis test.
1- What is prenatal genetic diagnosis test (prenatal diagnosis test)?
Prenatal diagnostic test is a non-invasive prenatal test that helps to screen for chromosomal anomalies and genetic disorders that can be seen frequently in babies with extracellular DNA analysis. What needs to be specifically mentioned and underlined is that this test does not currently provide a definitive diagnosis and is still a screening test.
2- For what purpose is the genetic diagnosis test performed? ?
This test is especially useful for diseases such as Down syndrome (trisomy 21), Edwards syndrome (trisomy 18), Patau syndrome (trisomy 13), known as chromosomal diseases, as well as sex determination and sex chromosomes. It is applied as an auxiliary method in the diagnosis of genetic diseases that develop due to blood incompatibility, RH determination of babies of couples with blood incompatibility, and some less common genetic diseases.
3- To whom should this test be recommended?
In its infancy, this test was performed on pregnant women over the age of 35 or those with a risk detected during ultrasonography, those with a previous history of birth with genetic problems, those with genetic diseases in couples or first-degree family members, and more recently, extracellular DNA DNA test has been performed. It is recommended that all couples have it done by explaining its advantages and disadvantages, including analysis. The issue of who and when the test will be performed has not yet been clarified in the literature.
4- When should the test be performed?
Generally, such tests can be done after the 9th week of pregnancy. The increase in the accuracy rate is due to the fact that the fractions of the baby in the mother's blood (baby It depends on the number of DNA fragments) increasing over time. Compared to the double screening test, which is the earliest test performed between 11-14 weeks, the prenatal diagnosis test can be performed earlier. This is an important advantage of the test.
5- Does performing the test harm the baby?
Prenatal genetics The diagnostic test does not harm the baby. It does not require surgical intervention and works only with a blood sample taken from the expectant mother.
6- How accurate are the test results?
This The accuracy rate of such tests is reported in most scientific publications; It has been shown to be over 99% for Down syndrome, 98% for trisomy18 and 99% for trisomy13. These rates are extremely high considering the importance of the diseases mentioned and are an important reason to get tested. However, there is also the possibility that the test may not yield results due to some factors related to the mother or the baby and technical reasons. The probability of experiencing such a negativity varies between 0 and 11% in the literature.
7- What information should be given to spouses before the test?
Before the screening test, spouses and their family history should be questioned and they should be told that the test is for screening purposes. It should be noted that the most effective screening test at the moment is the prenatal diagnosis test, and that the test has some weaknesses and may be repeated in some cases, and invasive interventions (such as amniocentesis) may also be performed when necessary. All screening tests depend on the preference of the spouses, and it is up to them to decide whether or not to have them done.
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