An Introduction to NIPT (Non-Invasive Prenatal Testing)
Non-invasive prenatal testing (NIPT) is a sophisticated screening method used to detect chromosomal abnormalities in a developing fetus. A blood sample taken from the mother is processed and analyzed for the presence of chromosome problems in the baby’s DNA. Unlike invasive testing techniques, such as Amniocentesis and CVS, this newest approach to genetic screening does not pose any miscarriage risk and is harmless to the baby.
What Does an NIPT Test Involve?
During pregnancy, the mother’s blood contains a small amount of genetic material from her baby, known as “circulating cell-free fetal DNA” or ccffDNA. In an NIPT test, the mother’s blood sample is processed to separate her DNA from the ccffDNA. The baby’s genome is then analyzed to detect abnormalities in certain chromosomes, which result in conditions such as Down Syndrome.
When Is an NIPT Test Performed?
Currently, NIPT tests are recommended for women with high-risk pregnancies. Risk factors include advanced maternal age, a family history of chromosomal abnormalities, or cases in which prenatal testing (ultrasound, serum screening) has shown a risk for Down Syndrome or other genetic conditions.
The test is currently validated and indicated for singleton pregnancies at 10 weeks gestation or older. Test results are usually available in 10 days to 2 weeks.
Women interested in taking an NIPT test should discuss it with their obstetricians.
What Does an NIPT Test Screen For?
The screening analyzes the baby’s DNA to detect the risk for chromosomal conditions Trisomy 21 (Down Syndrome), Trisomy 18 (Edwards Syndrome), Trisomy 13 (Patau Syndrome) with a high degree of accuracy.
How Accurate is NIPT Testing?
There are several companies currently providing NIPT test kits in the region that claim a high level of precision. For detecting Down and Edwards Syndromes risk, the average risk factor accuracy is 99 per cent. Accuracy rates for Trisomy 13 are between 80 and 92 per cent.
There are a few NIPT alternatives available in the market, including Prenatest from Lifecodexx, Germany which is the only CE-IVD approved prenatal diagnostic test which is validated with a European collaborative validation study.
It is important to remember that NIPT testing determines only the risk level for genetic abnormalities. The results do not definitively show if a baby has a genetic abnormality or not, but the chances are very high that if the test results show a problem, there is one.
False positive rates, or the number of tests that indicate a chromosome problem when none is present, are between 0.5 and 1 per cent.
When a test result is positive, meaning that it shows a high risk for a genetic condition, an Amniocentesis or CVS test is usually recommended.
Also important to keep in mind is that the NIPT tests currently on the market only screen for the particular chromosome abnormalities mentioned here. As this type of screening becomes more popular, a broader range of genetic tests will likely become available.