Prenatal testing of chromosome disorders


Non-invasive prenatal genetic testing (NIPT) is the latest and most precise screening method for detecting aneuploidy, and it is based on sequence analysis—second-generation sequencing of cell-free foetal DNA (cffDNA) in the mother’s blood circulation. NIPT analysis requires 10 ml of a pregnant woman’s blood and the procedure is no more dangerous than taking a routine blood sample.

cffDNA is detectable in maternal plasma as early as in 4 weeks after conception. However, the earliest time for conducting NIPT is between 9 and 11 weeks of pregnancy because cffDNA percentage should be more than 4% of the total amount of cell-free DNA. The half-life of cffDNA is short, about 30 minutes, and it is no longer detectable in the maternal blood a few hours after the delivery, which means that a woman’s earlier pregnancies do not affect the outcome of NIPT.

In particular, the use of the NIPT method in prenatal diagnostics can reduce the number of women undergoing risky and stressful invasive procedures. These include pregnant women whose foetuses do not actually have chromosome disorders but who are sent to undergo amniocentesis or chorionic villus sampling due false positive results in the screening. Changing NIPT from the current research-intensive method to a staple of clinical practice will significantly reduce the price of NIPT and make it available for the majority of pregnant women. This progress would increase the accuracy of prenatal genetic testing and reduce the risk of miscarriages resulting from invasive procedures.


PhD Kaarel Krjutškov

Principal Investigator, CCHT

Assistant Professor, Stockholm Karolinska Institute

This article was supported by the European Regional Development Fund through Estonian Research Council.

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