Class Action Alleges Labcorp’s MaterniT 21 Genetic Tests Have ‘Very High’ Rate of False Positives

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Laboratory Corporation of America (Labcorp) faces a proposed class action that alleges the company’s MaterniT 21 non-invasive prenatal test has a very high rate of false positives. 

The 17-page case also alleges Labcorp fails to advise patients who order its MaterniT 21 test that they should undergo genetic counseling before and after taking the test to understand the results and their predictive value. More importantly, the lawsuit says, Labcorp does not inform the doctors who recommend the MaterniT 21 test that a positive result is “likely to be a false positive that is not actually a cause for concern.” 

Overall, the lawsuit alleges MaterniT 21 test buyers have been misled into paying as much as $500 for the genetic test “under a false or at best incomplete understanding” of what it provides. 

The complaint relays that non-invasive prenatal tests, such as the MaterniT 21 test, are blood-drawn tests for pregnant women that can screen for certain chromosomal abnormalities that could affect a baby’s health and development. Per the case, parents traditionally could only screen for genetic conditions later in pregnancy through invasive procedures such as amniocentesis, which requires a needle to be inserted into the amniotic sac surrounding the baby to test its genetic material. Whereas amniocentesis carried a “very small, but existent risk of miscarriage,” non-invasive prenatal tests have been marketed as a significant, safer advancement given the tests utilize a baby’s genetic material present in the mother’s blood, the suit relays. 

Despite these representations, however, a New York Times investigation revealed this year that the positive results from some non-invasive genetic tests are incorrect about 85 percent of the time, producing a high rate of false positives, the lawsuit states. 

“False positive results in prenatal testing carry severe consequences. Many times, expecting parents, and specifically pregnant mothers, are subject to invasive diagnostic prenatal testing and significant additional medical diagnosis and care as their pregnancy may be labeled as a ‘high risk’ pregnancy. This is not to mention the severe anxiety and stress about the health of their child that false positive [non-invasive prenatal test] results cause soon-to-be parents.”

The suit relays that the plaintiff, a Riverside, California resident, was advised by her healthcare provider in May 2020 to undergo prenatal screening to find out if her baby had any potential genetic abnormalities. Based on the information provided by Labcorp through her doctor, the plaintiff understood the MaterniT 21 test as an accurate way to test for possible genetic conditions, the case stresses. 

Prior to ever receiving her MaterniT 21 test results, however, the plaintiff was informed by her doctor that her baby had tested positive for Turner syndrome, a genetic disorder that causes medical issues including short height, heart abnormalities and a lack of formation of reproductive organs, the lawsuit states. The complaint contends, however, that the plaintiff was never informed that Labcorp’s test results have a very low positive predictive value for Turner syndrome and other chromosomal abnormalities, and that the MaterniT 21’s false positive rate for Turner syndrome is as high as 74 percent. 

Similarly, neither the plaintiff nor her doctor was informed before the woman even took the test, or before she received the results, that the test is “meant to be a screening test only that has significant limitations” as far as predictive value on any positive result, the filing says. 

“Critically, even when Plaintiff received the actual test report after the phone call with her healthcare provider, it did not disclose the false positive rate of the positive test result that she received, and in fact disclosed that it had a sensitivity rate of ‘96.2%’ for ‘Sex Chromosome Aneuploidies,’ which would include Turner Syndrome, and a specificity rate of ‘99.7%’ for such disorders. This is important because the sensitivity rate is traditionally used to indicate the rate of false negatives, while the specificity rate is used to indicate the rate of false positives.”

According to the complaint, the plaintiff's daughter, despite the test results, was born with "no abnormal health conditions."

The lawsuit looks to cover all purchasers of Labcorp’s MaterniT 21 testing services, including consumers who paid out of pocket, through health insurance or through any other collateral source. 

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