Hong Tran

Two of the world's largest professional societies of human geneticists have issued a joint position statement on the promise and challenges of non-invasive prenatal testing (NIPT), dau gio xanh a new procedure to test blood drawn from pregnant mothers for Down syndrome and other chromosomal disorders in the fetus. The document addresses the current scope of and likely future improvements in NIPT technology, ways it may best fit with existing prenatal screening tools and protocols, options and priorities in its implementation, and associated social and ethical issues.

The statement, drafted by the Social Issues Committee of the American Society of Human Genetics (ASHG) and the Public and Professional Policy Committee of the European Society of Human Genetics (ESHG), was published online March 18 in the European Journal of Human Genetics.

Current prenatal screening protocols for common structural abnormalities in the chromosomes vary among countries and medical practices. Generally, though, pregnant women are offered a combined first-trimester screening (cFTS), a risk assessment test based on blood and ultrasound markers. Women who receive abnormal cFTS results undergo a second step of testing to confirm or deny whether the fetus has an abnormality such as Down syndrome. This second step involves invasive procedures, such as amniocentesis, that in 0.5-1% of cases may lead to a miscarriage.

One important drawback of cFTS is the high rate of false alarms that lead to invasive procedures that put pregnancies at risk when the fetus is actually chromosomally normal. The main benefit of NIPT, apart from a significantly higher detection rate, dau xoa bop is that it dramatically lowers the false alarm rate from about 5% to about 0.2%, making prenatal screening more accurate and safe. This is achieved by analyzing fragments of DNA in maternal blood, some of which provides information about the fetus. The fact that this 'fetal DNA' actually derives from the placenta is one reason why NIPT is not fully reliable. An important implication of this is that women who receive an abnormal NIPT result should still be advised to confirm this result through a second step of testing if they are considering a termination of pregnancy, the statement authors write.

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