Dr Priya Kadam, Associate Director- Reproductive Genomics, MedGenome Labs shares insights on the importance of non-invasive prenatal testing during pregnancy to determine chromosomal abnormalities irrespective of any prior risk, screening should be advised as a part of first trimester screening in pregnant women
An unexpected outcome, as the world battles COVID-19, is the sudden focus on modern molecular testing techniques. These techniques have been around for a long time but are now coming into the forefront. Tests such as a RT- PCR have been around for a long time but are only now coming into the limelight. It’s safe to say that large portion of Indians now know what an RT-PCR test is. Molecular diagnostic is not only more accurate, but also non-invasive in some cases.
One such modern test is non-invasive prenatal screening test (NIPT). This is a test that can be used to detect common chromosomal abnormalities in unborn babies from as early as the 10th week of pregnancy. The technique is based on next generation sequencing. This technique is used to sequence the entire genetic code in humans to find genetic mutations that are causing disease and disorders. The benefits of the test are convenient sample collection and high screening accuracy of over 99 per cent. NIPT also offers increased safety compared to invasive procedures such as Amniocentesis and Chorionic Villus Sampling (CVS).
Experts advice universal prenatal screening for common chromosomal disorders as part of first trimester screening in pregnant women. Take the case of a couple from Mumbai already evaluated and found harbouring an existing genetic condition which can cause a serious disease in their offspring. The couple opted for an assisted pregnancy through a young egg donor to eliminate the risk to the offspring being born with the disorder. The donor was evaluated for the same condition and found normal. This ensured her egg could be used to conceive a child without the genetic condition the couple harboured. Since it was a precious pregnancy the couple further decided to undergo a non-invasive prenatal testing to assess for any other common conditions that may occur spontaneously. Unfortunately, the foetus was found to be at high risk for Trisomy 21 (Down Syndrome). This highlights the fact that though women with advanced maternal age (35 years and above) are more prone to common chromosomal abnormalities, the condition should also be evaluated for in younger women. Both the donor and the woman carrying the pregnancy were less than 35 years of age.
Hence, screening for chromosomal abnormalities irrespective of a prior risk information is important and should be advised screening irrespective of age, other genetic conditions and backgrounds. In addition to testing, the couple should undergo genetic counselling to ensure that they are aware of the risks involved and understand the test results. A comprehensive discussion should be had with the family doctor or a health advisor about the tests available and the way forward after the tests results are available.
The COVID lockdown brought NIPT into the forefront because it offers high accuracy screening with low risk of infection compared to invasive procedures such as Amniocentesis and CVS both of which may require hospital admission which can expose both doctor and patient to the risk of COVID infection. There has been increase in prescription of NIPT’s due to the COVID lockdown. The reasons could be multifactorial, number of elective procedures in hospital had reduced during lockdown and there might have been patient reluctance as well for fear of COVID infection. NIPT is seen as a good alternative due to higher accuracy and minimum discomfort to the patient. This trend is likely to continue as reliability of NIPT is well established and more doctors are becoming aware of the utility of NIPT in the current circumstances.