Trisomy 21: new tests using maternity blood being questioned

In a press release dated November 18, 2015, the Supreme Health Authority published their first report on the performance of new tests using « Non-invasive Prenatal Screening” for Trisomy 21, which examines maternal blood for fetal DNA sequences from chromosome 21. These new tests could modify screening methods: studies are being carried out in France and the results are expected soon.

Currently, prenatal screening in France is based on measuring the

« nuchal translucency» of the fetus by sonogram, combined with analyzing serial markers during the 1st and 2nd trimesters of pregnancy. This screening establishes “a rate of risk” which, if over or equal to 1/250, may lead to proposing a complementary diagnosis by amniocentesis or Chorionic villus sampling (CVS) to determine the fetal karyotype. These invasive exams lead to the loss of 1% of fetus, whether they might be healthy or carriers of a certain pathology.

In France, the 2011 bioethics law has made it compulsory to inform all pregnant women, regardless of their age, on the possibility of having access to combined screening for Trisomy 21 as early as the first trimester of their pregnancy. The changeover towards having these early tests performed happened very quickly: in 2013, the combined tests in the 1st trimester represented 73% of the total of tests performed, compared to 2% in 2009.

For the moment, Non-invasive Prenatal Screening in France is neither authorized, nor listed in its nomenclature, nor recommended in its screening policy; but it is already certified in France and marketed by the Cerba laboratory who announced to have already practiced 6,600 tests for fetal Trisomy 21.

At the General Direction of Health’s request, the French Supreme Health Authority analyzed the data in the literature regarding the performance of these new tests. The data demonstrate that the detection rate for Trisomy 21 by this screening is greater than 99%, and the rate of false positives less than 1% in the group of women identified to be at risk. But in cases of positive results with this new test, the confirmation of the diagnosis still depends on establishing the fetal karyotype following amniocentesis or Chorionic villus sampling.

The French Supreme Health Authority considers that the current means of screening Trisomy 21 should therefore be reviewed. The French National Consultative Ethics Committee also gave a favorable opinion for these tests in April 2013. The Supreme Health Authority will conduct this work with experts and health professionals, notably by consulting the results of the French studies in progress.

In its evaluation, the Supreme Health Authorities must take into account ethical, economical and organizational stakes, to specifically define the place for these tests in the screening strategy for Trisomy 21 in France.

The possibilities of Non-invasive Prenatal Screening will now go above and beyond research for Trisomy 21, since the fetal genome can be entirely sequenced. For Dr. François Jacquemard, obstetrical gynecologist, and coordinator at the American Hospital in Paris and one of the 49 multi-disciplinary Prenatal Diagnostic Centres certified in France: « With access to fetal DNA, we enter a new era ». To which Jean-Yves Nau, journalist and medical doctor, responds:  « He didn’t say which era we are entering. And that is really a shame. »

Via these tests, potential handicaps will be known before the 12-week pregnancy limit allowed for an abortion. In this manner, there would be no more testing, nor possible complementary exams or discussions before medical interruptions of pregnancy. It’s therefore an open road towards « eugenic » abortions.


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