21 April 2022

The FDA warns

The results of non-invasive prenatal genetic tests need to be verified

Elena Kleshchenko, PCR.news

The US Food and Drug Administration (FDA) has published a message reminding that genetic non-invasive prenatal screening tests (NIPT, NIPT) can give false results and require further diagnostic confirmation.


NIPT reveals signs of abnormalities in the fetal DNA, which is contained in the blood of a pregnant woman. Although healthcare providers often use them, the FDA has not yet approved any of them, has not evaluated their accuracy and effectiveness. These tests are used as screening, but not as diagnostic: they may indicate a possible risk of genetic abnormalities in the fetus, but their results must be confirmed by diagnostic tests. In turn, test manufacturing companies must also comply with certain rules when offering their products.

In its warning, the FDA refers to reports on patients and medical professionals who have made important decisions, for example, on termination of pregnancy, solely based on the results of NIPT without confirmatory diagnostic testing.

Also mentioned are "concerns expressed in recent media reports." Probably, we are talking about a January article in The New York Times, which tells the dramatic stories of women who have received false positive NIPT results (it is indignantly reported that positive results are incorrect in 85% of cases). The authors even draw a parallel between suppliers NIPT and the infamous Theranos startup (although it is stipulated that "unlike Theranos, the ability of these companies to test blood for common diseases is not in doubt"). However, they do not explain the difference between screening and diagnostic tests.

"Many laboratories offering these tests advertise them as "reliable" and "highly accurate," offering patients "peace of mind." The FDA is concerned that these claims cannot be supported by reliable scientific data. (...) There are limitations due to the rarity of some of the conditions included in the screening. For example, when screening for a very rare disease, a positive result may turn out to be a false positive rather than a true positive," the FDA said.

Patients are advised to discuss this with a medical genetics consultant before choosing whether to use NIPT and which one, and not rely solely on the results of NIPT when deciding whether to maintain or terminate pregnancy. The FDA advises healthcare providers to also familiarize themselves with the recommendations for patients, take into account technical and biological factors that can affect the results of NIPT, and carefully explain the risks and benefits to patients. Doctors should not rely solely on the results of NIPT in the diagnosis of chromosomal abnormalities and other disorders.

Industry analysts believe that these recommendations will not bring significant changes for NIPT developers, such as Natera. "The safety message does not highlight any new data, details or facts that have not been well known to those who have been following the NIPT for many years — the NIPT has been designed for screening since its inception, and any positive result must be confirmed," notes Alex Novak, analyst at Craig—Hallum, in a note for investors. In fact, the FDA document simply reminds of the need to follow existing recommendations. In his opinion, the biggest disadvantage for Natera is the support of the opinion that its shares may fall in price, but it is hardly justified: so far there is no fall.

Novak suggests that Natera will seek FDA approval for its tests. The company can use the recent results of the SMART study, which evaluated the accuracy of the NIPT Panorama screening test. The test detects trisomies on chromosomes 21, 18, 13, deletion 22q11.2 and other deletions, anomalies in the number of sex chromosomes and triploidy. The SMART study involved more than 20,000 patients over five years at 21 medical centers in the United States and other countries. As reported in two articles published in January 2022, Panorama demonstrated high sensitivity and specificity for trisomies (98.98 and 99.95% for trisomy 21) and less high but impressive results for deletion 22q11.2.

The FDA explains that NIPT is currently marketed as laboratory developed tests (LDT), for which regulatory compliance is not usually ensured. However, the FDA "continues to work with Congress on legislation to create a modern regulatory framework for all tests, including LDT."

Portal "Eternal youth" http://vechnayamolodost.ru

Found a typo? Select it and press ctrl + enter Print version