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Studies Prove Inaccuracy of Prenatal Genetic Testing by Bridget Ryder

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Studies Prove Inaccuracy of Prenatal Genetic Testing

A prestigious fertility clinic in New York City has shown that the genetic screening of embryos routinely accompanying in vitro fertilization (IVF) contributes to the “deselection” of healthy humans who are then either left to die, donated to science, or interminably frozen. 

Pre-implantation Genetic Testing for Aneuploidy (PGT-A) has been used in IVF for about two decades, touted as a way of increasing the success of the procedure. But research conducted by the Center for Human Reproduction (CHR) has shown the opposite to be true—such testing “may reduce the chance of pregnancy in association with IVF.” 

In an April 22nd press-release, the CHR announced that it had published the results of the transfer of 50 embryos that had been deemed “abnormal” by other clinics after PGT-A screening. While these other fertility clinics prohibited the transfer of “abnormal” embryos to the mother’s womb, the Center for Human Reproduction had been allowing such embryos for transfer, a procedure completed in their New York clinic, for several years. 

Among those embryos, 16% survived to a live birth, and none of them were born with birth defects or chromosomal conditions such as Down’s Syndrome. One baby had a heart defect at birth that was able to be treated with surgery, but there was no evidence that the defect was related to any chromosomal irregularity. 

PGT-A is a biopsy of a small selection of cells from a five-day old embryo to check if they have the usual 26 chromosomes—13 from the father and 13 from the mother—necessary to form the DNA of the new person. If there are extra or missing chromosomes, aneuploidy, found in the cells, the embryo is deemed “abnormal,” and most clinics refuse to transfer them to the mother’s womb. This leaves parents having to decide what to do with these embryos—freeze them, let them die, or donate them to science. 

Evidence for the futility of these genetic tests emerged years ago, according to CHR.  In response, the New York clinic changed its practice and in 2014 began transferring “abnormal” embryos. But across the fertility industry, PGT-A is still a widely offered service at IVF clinics. CHR estimates that currently about half of IVF cycles include the test.  

Despite advances in the understanding and even the treatment of chromosomal conditions such as Down’s Syndrome, the birth of embryos once diagnosed as ‘abnormal’ shows how much remains to be understood about human development and genetics, as well as the unreliability of PGT-A tests. 

FDA warns against prenatal genetic screenings

In another blow to widely practiced prenatal genetic screening, the United States’ Food and Drug Administration (FDA) issued a warning earlier in April about the use of non-invasive prenatal screenings (NIPS). The FDA cautioned that although these tests are widely used to check the foetus for Down’s Syndrome and other genetic conditions, none of them have been approved by the FDA, and they often provide false positives. The agency explained that these tests are not suitable for prenatal diagnosis of genetic conditions. 

The FDA decided to issue the warning after having received reports that NIPS tests were being used to make medical decisions, often based on misleading information.

“Specifically, pregnant people have ended pregnancies based only on the results of NIPS tests.… The FDA is aware of cases where a screening test reported a genetic abnormality and a confirmatory diagnostic test later found that the foetus was healthy,” a statement on its website said. 

Hopefully medical practice will catch up quickly with the science.

Bridget Ryder is Spain-based writer. She has written on politics, environment, and culture for American and international publications. She holds degrees in Spanish and Catholic Studies.