Prenatal Diagnostic Paper

Prenatal diagnosis has become of of the most important factors of the obstetrics practice, it diagnoses any complications or possible disorders, especially trisomy 21 (Down’s syndrome) of the unborn baby. The most common methods for prenatal diagnosis of trisomy 21 require invasive procedures, which includes Amniocentesis and Chorionic Villus Sampling (C.V.S), where it uses a sample of the fetal tissues. These two options carry a small but definite risk. Therefore, they could cause more miscarriages than they would detect aneuploidy (Norwitz & Levy, 2013). Due to this problem, a wide range number of non-invasive techniques have been developed and introduced over the last few decades, such as combining ultrasonographic examination of the fetus and and measurements of several hormones of the material in order to increase the effectiveness of identifying disorders. Nonetheless, this combined technique still required invasive testing (Chiu et al.,2011). However, in the recent years, with the technology advances in molecular genetics, it has helped to discover a new technique of non-invasive prenatal diagnosis through analyzing the circulating cell-free fetal DNA present in the maternal blood sample. This method is considered an extremely crucial development in prenatal care. Amniocentesis and Chorionic Villus Sampling (C.V.S) are invasive procedures that require the fetal cells to be directly taken out from the placental, fetal urine, or skin during pregnancy for genetic analysis which could possibly bring the risk of hurting the fetal. But with the non-invasive testing by using cell-free fetal DNA, performed by obtaining maternal blood only, it helps to avoid any direct contact with the growing fetus and reduces the risk of affecting the fetus health (Palomaki et al.,2011). In 1997, Y M Dennis Lo, Noemi Corbetta, Paul F Chamberlain, Vik Rai, Ian L Sargent, Christopher W G Redman, James S Wainscoat, performed an experiment to find out whether or not fetal DNA is present in maternal plasma and serum for cell free DNA testing. It was concluded that the fetal DNA was presented in maternal plasma/serum, therefore, the application of maternal plasma/serum for non-invasive prenatal testing is possible (Lo et al., n.d). Thanks to the results of the initial experiment, it has generated an interesting non-invasive method for finding …show more content…
In this study, cell free fetal DNA was being combined with a new technical advance in the analysis of fetal DNA called “massively parallel sequencing”. This technique is capable of measuring a small increment of chromosome 21 DNA, as well as the entire fetal genome from the maternal plasma, and made it possible for millions of DNA particles in biological samples to be identified within the matter of days. Two protocols with different levels of multiplexing, 2-plex and 8-plex sequencing, were being employed to study. With 2-plex protocol, trisomy 21 fetuses were detected at 100% sensitivity and 97.9% specificity. The 8-plex protocol, trisomy 21 fetuses were detected at 79.1% and 98.9% specificity. This allows fetal trisomy 21 to be identified in high-risk pregnancies with high sensitivity and specificity, and more accurate.
With this cell-free fetal DNA technique, it assists to detect disorders a lot quicker because cell-free fetal DNA was designed to have early access in pregnancy without having the possibility of hurting the fetal, which leads to better pregnancy decision making and management. Many countries around the world including the U.S are offering as well as expanding cell free fetal DNA tests (Agarwal et