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Anxious for Nothing

A new study shows many prenatal genetic tests are wrong more than 80 percent of the time, producing countless false positives.

It is at once both the most distinctly human behavior and the most technically de-humanizing that we have chosen to wield advanced science for no nobler end than designer babies. And for the plebes, the knock-off option: prenatal genetic tests for every disability you could imagine. Knowledge is power.

A new study reported on in a widely circulated article in the New York Times last week showed that several major prenatal genetic tests, however, are wildly off target. The five most common microdeletion tests—microdeletion tests screen for missing pieces of chromosomes that can result in a variety of intellectual disabilities—were all wrong more than 80 percent of the time.

The tests the Times studied were as much as 93 percent inaccurate. On average, for every 15 times they correctly identified a problem, they misidentified it another 85 times. They weren’t just wrong, moreover, but skewed heavily to the side of false positives. In effect, these tests are weighted to say a baby’s life will not be worth living.

It’s a jarring statistic, not least because some mothers will choose to abort their child if such tests come back positive.

The Times describes several cases in which follow up testing revealed babies thought to be missing parts of chromosomes were in fact healthy. Not everyone takes a second test, however. Writes the Times: “A 2014 study found that 6 percent of patients who screened positive obtained an abortion without getting another test to confirm the result. That same year The Boston Globe quoted a doctor describing three terminations following unconfirmed positive results.” Much has changed since 2014, but more comprehensive data on the current rate of abortions done after erroneous testing has yet to be collected.

More reliable than microdeletion tests, the typical “follow up” procedure involves removing a piece of the mother’s placenta to see if it confirms the first tests’ results. Because placenta tests can cost thousands of dollars, and come with their own risks, which include miscarriage, it’s not hard to see why mothers don’t always immediately choose to go through with this. Moreover, placenta cannot be extracted until later in the pregnancy, sometimes past the point where abortions are legal in a given state.

When my husband and I went in for a routine first trimester checkup this fall, we were encouraged to take a litany of tests to ensure our baby didn’t have any problems. The recommended list was about 15 tests long, despite the fact that we are in a low-risk category. My husband asked if there was any reason to take the tests, if we planned to carry the baby to full term regardless? Was there anything we could do if we knew our child had one of these genetic disabilities before birth? The nurse, after much talk, admitted that for the most part there was not.

The Times journalist admits this, too, however inadvertently. The 32-year-old woman featured in the article is devastated that, after months of fertility treatments, she is going to have to abort her baby because one test suggested he was missing part of a chromosome. Fortunately for Emmanuel, her now-six-month-old son, she took a placenta test which showed the first to be wrong. It’s hard to miss the tragedy here. For the writer, it is the poor woman who almost didn’t get to be a mother because of a faulty test. For the rest of us, it’s the poor mother who almost killed her son rather than face the potential of raising a child with a genetic disorder. Either way, for such prenatal diagnoses that are correct, at least for now, there are few corresponding prenatal treatment options beyond the antiseptically termed “pregnancy termination.”

Prenatal genetic tests are encouraged the same way so many other preventative medical tests are—that is, doctors will often assume a mothers wants at least some of the screenings until she suggests otherwise. The prenatal genetic testing market, estimated to be worth $600 million dollars, advertises such tests as a way for mothers to be “more prepared” and to have “peace of mind” about their child’s health. For the women the Times interviewed, however, most described considering abortions after receiving the false positive tests. All of the women recounted severe anxiety over the diagnoses, which their doctors presented as highly accurate.

As the writer points out, a key problem is that the FDA does not regulate this kind of test, meaning not only can test makers continue to market their product as successful, despite high rates of failure, but there are also few limits on what kinds of new tests they can offer vulnerable new moms. This also means doctors who have only read the marketing brochures for a given test may encourage a false sense of trust in the tests’ accuracy. At least once, the FDA has considered regulating the industry, but has refrained.

It’s a reflection on our age that the demand for these tests for niche diseases—some of which affect as few as 1 in 100,000 babies—is expected to double by 2025. We, particularly mothers, with the world at our fingertips through technology, are readily and constantly inundated with new and obscure things to be anxious about. Whether our child is actually at risk for any of the given diseases is irrelevant, once the possibility enters the mind. All it takes is one mom posting on the Reddit thread that she had heart palpitations at week 12, and suddenly hundreds of other women want to know: Is this normal? Or, more to the point, Is that me? 

Indeed, the whole experience of modern pregnancy seems fraught with potential objects of concern. Many are not entirely rational. Because women are more susceptible to foodborne illnesses during pregnancy, for example, they are told to overcook absolutely everything, avoid farm fresh milk, and microwave even precooked luncheon meat. (Whether said meat is developed in a lab or pumped full of hormones and chemicals through factory production, meanwhile, is never a concern.) Pregnant mothers are also encouraged to get a “healthy” amount of polyunsaturated fats, found most readily in vegetable oils. These are the same oils that have been linked to increased blood pressure, hypertension, and risk of cardiovascular diseases, for which the truly “healthy” amount is none—yet they are recommended to women at a time when the female body is at a higher-than-normal risk for heart issues.

What we lack in true science, we can make up for in statistics, but all of these facts and figures do not add up to wisdom. What does it matter, for example, that less than 1 in 4,000 babies are born with DiGeorge syndrome? The chance of that test being wrong may not even enter a mother’s mind once she’s been told with the authority of “Science” that her child belongs to that fraction of a percent.

Fear is a powerful motivator. The test creators are not fools. What these labs have capitalized on is our innate desire to know, in order to control. But as my own nurse admitted, even accurate test results can only get you so far. Knowledge, as it turns out, is not always power—at least not where mistakes masquerade as truth.

The next question we should ask is whether the desire for such knowledge is good, even for those who won’t abort their child. When it can’t lead to preventative treatments, and can’t even be trusted as truth, it only serves to stir up the heart to a state of gnawing anxiety.

Who can add a hair to his head by worrying?



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