Question

How is this new technique of Noninvasive Prenatal Testing (NIPT) superior to the older techniques of amniocentesis and Preimplantation Genetic Diagnosis (PGD)?

Answer 1

Ans) Prenatal detection of chromosome:

- Abnormalities has been offered for more than 40 years; however, invasive testing also carries a risk for procedure-related miscarriage. For this reason, a number of noninvasive tests have been developed.

- Fetal DNA can be detected in as little as 10 μL of maternal plasma and serum, in amounts significantly higher than that available from nucleated blood cells extracted from a similar volume of whole blood. The approach of using cell-free fetal DNA instead of fetal cells provided a far easier, less labor intensive, and less time consuming way to work with fetal DNA derived from the maternal circulation, and this opened up new opportunities for noninvasive prenatal testing (NIPT).

- Noninvasive testing grew out of a desire to avoid direct contact with the growing fetus/placenta and concomitantly risking the health of the fetus. NIPT refers specifically to techniques that evaluate fetal cells or cfDNA in a blood sample drawn from the mother during pregnancy.

- The diagnostic scope of traditional prenatal cytogenetic analysis has recently been extended to include detection of microdeletions and microduplications using new genomic technologies such as microarray analysis.

- There are currently two primary next-generation sequencing approaches for gathering genetic data from cellfree DNA: massively parallel shotgun sequencing and targeted sequencing.

- A number of companies have been spearheading the effort to develop a reliable and accurate commercial NIPT for fetal aneuploidy detection. Although the precise technology used by each of these companies varies, they all rely on the same premise: that existing high-throughput approaches to DNA sequencing coupled with sophisticated data analysis will be able to detect abnormal amounts of chromosome-specific cfDNA in the maternal circulation in those pregnancies with fetal aneuploidy.