— We must regulate LDTs that carry risk

by Stephanie Rogus, PhD, RDN, and Peter G. Lurie, MD, MPH 

Imagine nearly ending a pregnancy because a lab test was wrong. In January 2022, a story in the New York Times recounted one pregnant woman’s experience with an inaccurate genetic non-invasive prenatal screening (NIPS) test. These blood tests analyze small pieces of fetal DNA that cross the placenta into the mother’s circulation to assess the risk for genetic abnormalities in the fetus. Though NIPS tests for more common conditions like Down syndrome are very useful clinically, tests for serious but rare conditions like Prader-Willi syndrome — a condition associated with distinctive facial features, poor muscle tone, weight gain, and behavioral disturbances — are prone to false-positives. Because Prader-Willi is so rare, it is actually more likely that a positive test is false than true.

And that is exactly what happened in this case. After her test came back positive for fetal Prader-Willi syndrome, the woman contemplated terminating her pregnancy. Luckily, she underwent a follow-up invasive procedure and learned that the initial result was indeed a false-positive. She went through with the pregnancy and delivered a baby with no indication of Prader-Willi syndrome. But it was a close call and the psychological toll was immense.

NIPS tests are a type of medical device called laboratory-developed tests (LDTs). Unlike conventionally manufactured medical devices, LDTs are developed and used in one laboratory and providers send their tests to that facility. At first, LDTs were largely confined to isolated academic laboratories, but with time the number and complexity of such tests has burgeoned as companies are increasingly offering them for more common conditions.

Link to article in MedPage Today by Stephanie Rogus



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