Recent technological advances are enabling the development of new screening tests that make medical procedures less invasive and more affordable.
Indeed, new molecular genetic technologies have facilitated non-invasive prenatal testing (NIPT) through the analysis of cell-free fetal DNA (cffDNA) in maternal plasma.
This is a profound development in prenatal care that represents a substantial improvement over traditional multiple marker screening.
Science and medicine are bringing about innovations shifting the paradigm of current clinical approaches.
In fact, prenatal testing aims to give families and doctors the earliest and most complete information on eventual chromosomal disorders in the fetus.
Mainly focused on Down syndrome it started around 1970 and went through several significant improvements.
At first, it was performed by non invasive methods of lower accuracy, then reached its maximum accuracy with fetal cellular testing by chorionic villus sampling (CVS) and amniocentesis.
These two methods are highly invasive and generate distress for the mother. They involve inserting a needle into the womb to take a sample of the baby’s genetic material and have an average risk estimated at 1% risk of miscarriage.
Cell- free fetal DNA screening has been introduced in 2011 in several countries and requires a simple blood draw from an expectant mother to analyze fragments of fetal DNA that have been released into her bloodstream and detect genetic abnormalities such as Down syndrome.
Small fragments of genetic material, called cell-free DNA circulate freely in every person’s bloodstream.
In a pregnant woman it includes not only maternal DNA but also fetal DNA from the 5th week of gestation in a quantity between 2-40%.
This cell-free fetal DNA originates from the shedding of placental cells and reflects the genetic makeup of the developing baby.
It is continually released into the pregnant woman’s bloodstream, starting in small quantities during the first trimester and increasing throughout pregnancy.
This cell-free fetal DNA is completely absent from mothers bloodstream a few days following the delivery.
Today Next Generation sequencing technologies have made it possible to analyze with high reliability the cell-free fetal DNA in the mother’s bloodstream, providing comprehensive screening and excellent accuracy at an unprecedented speed.
Sequencing information is analyzed using bioinformatics: this enhanced algorithm compares the sequenced fragments to the human genome of reference and evaluates statistically the number of the chromosome in the fetus to determine the presence of aneuploidies.
An aneuploidy in a pregnancy is detected when the calculated number of a chromosome is different than expected.
What is an aneuploidy?
It is a term used to describe a numerical chromosomal abnormality in humans that is caused by an extra or missing chromosome and is the leading genetic element of miscarriage and congenital birth defects.
Since the identification nearly a half-century ago of the first human aneuploidy condition, a great deal of information has accrued on its genesis.
Cell-free DNA screening has been reported to have a detection rate for trisomy 21 (Down syndrome) of more than 99% with a false positive rate as low as 0,1% implying it should not be limited to only high risk pregnant women but could be performed in all patients, including low-risk ones.
The Royal College of Obstetricians & Gynecologists (RCOG) states that in time, this technology is likely to become the primary screen for chromosomal abnormalities in pregnancy and recommends that women be offered prenatal assessment for aneuploidy regardless of maternal age.
The increased accuracy of non-invasive prenatal tests means less women would be unnecessarily referred for invasive tests such as amniocentesis or chorionic villus sampling to confirm suspected cases of Down’s Syndrome.
Thanks to the detection of fetal fraction, Genoma’s non-invasive fetal DNA screening test for trisomies and sexual aneuploidies, Tranquility is most accurate.
For further information visit Tranquility, the most complete non-invasive cell-free fetal DNA screening for Trisomy disorders and sexual aneuploidies.
Before you undergo prenatal cell-free DNA screening, your health care provider or a genetic counselor will explain the possible results and what they might mean for you and your baby.