Maternal serum screening tests for pregnant mother is a kind of prenatal screening test. These screening tests give a prediction that a pregnancy is affected by a chromosome abnormalities or certain developmental problems or not, but do not give a definite diagnosis. They are used to segregate women into ‘high risk’ or ‘low risk’ categories. And based on the results pregnant women are advised to go for the diagnostic tests. These conditions are caused by addition or deletion extra or missing chromosome in the developing baby. Maternal Serum Screening is a simple blood test which is done inearly weeks of pregnancy to screen for Down syndrome, Trisomy 18, Trisomy 13 and open neural tube defects. It further is subdivided into three categories: Double Marker Test, Triple Marker Test, and Quadruple Marker Test.
First trimester maternal serum screening test can identify a pregnancy with a high risk of Down’s and Edward syndrome. This test is done in between 11-13 weeks of pregnancy. Second trimester maternal serum screening test looks for high risk of Down syndrome, Edward syndrome or neural tube defects. This test is done in between 14 and 20 weeks of gestation.
All women have the chance of having a baby with some chromosomal abnormalities like Down syndrome or Edward syndrome and Patau syndrome, and the chance increases with the age of the woman.
Chorionic villus sampling (CVS) and amniocentesis are the confirmatory and diagnostic tests that will detect chromosome abnormalities such as Down syndrome and Edward syndrome and Patau syndrome in the unborn baby.
Noninvasive prenatal test (NIPT) is a simple and safe blood test which is performed on the mother by just taking a blood sample. NIPT test generally screens for all the common and major chromosomal aneuploidies in the unborn baby. This genetic test gives a prediction on the occurrence of trisomy 21 (Down’s syndrome), trisomy 18 (Edward syndrome) and Trisomy 13 (Patau syndrome). Apart from these common abnormalities other chromosomal and sex chromosomal aneuploidies are also detected with the NIPT test. This is a genetic test during pregnancy with no risk to the baby. NIPS genetic test is performed within 10 – 20 weeks. At the time of pregnancy, cell free DNA of the baby travels to the mother’s blood stream and floats along with her own DNA. ClariT NIPS test accurately screens for the fetal cell-free DNA in the mother’s blood stream to detect the occurrence of Down’s syndrome and other Trisomy conditions as well. Individuals normally have 23 pairs of chromosomes and each chromosome is made up of DNA containing our genetic information in the form of genes. Down syndrome occurs when there an extra copy of chromosome 21. The presence of this extra genetic information is the reason of physical and mental characteristics that occurs in people with Down syndrome.
ClariT NIPT for Down syndrome works by analyzing the DNA fragments present in the maternal blood plasma. Most of this comes from the mother, but in addition about 10%-20% of it comes from the fetus. Therefore, by analyzing all the DNA sequences linking to individual chromosomes, the total amount of chromosome 21 in the mother’s blood can be compared with the amount of the other chromosomes. If the baby has Down syndrome, there is slightly more chromosome 21 than expected, showing that there is more of this particular chromosome in the sample than normal. In this way, the test results in a very accurate prediction.
