Down syndrome: prenatal diagnosis by DNA

A new method of prenatal diagnosis of Down syndrome has been developed

Copper News based on Science News: A more accurate prenatal test to predict Down syndrome

An international group of researchers has published the results of testing a new method of prenatal (intrauterine) diagnosis of Down syndrome (for the results of previous developments of similar technologies, see the articles "Prenatal diagnosis: blood test instead of invasive procedures" and "Safe method of early diagnosis of Down syndrome and other trisomies" – VM).

Their technology – the study of fetal DNA by analyzing the mother's blood – turned out to be much more accurate than standard screening methods. (See the press release of one of the groups of authors of the Great Ormond Street Hospital launches new safer, more accurate test for Down's Syndrome - VM.)

The study, the results of which are published in the New England Journal of Medicine (Norton et al., Cell-free DNA Analysis for Noninvasive Examination of Trisomy, in the public domain, and its summary of the Use of Cell-free DNA to Screen for Down's Syndrome in the NEJM – VM editorial), involved 15,841 pregnant women a woman. In about 3% of cases, the researchers were unable to obtain enough fetal DNA and perform an analysis. In the remaining 15,803 cases, screening gave 9 false positive results (0.06%). Standard screening of the same women gave 854 false positive cases (5.4%).

With a positive result of the new analysis, the chances that the child will actually be born with Down syndrome were almost 81%. With standard screening, only 3.4% of the positive results were correct.

Standard screening includes an ultrasound examination and a blood test of the mother for the content of certain proteins. If the results of these tests reveal the likelihood of Down syndrome in the fetus, doctors can conduct more accurate, but invasive tests – for example, amniocentesis (amniotic fluid sampling). With invasive diagnosis, there is a risk of miscarriage or infection. Therefore, the importance of the new screening method is the ability to reduce the need for invasive procedures.

Portal "Eternal youth" http://vechnayamolodost.ru02.04.2015