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Experts say you shouldn’t rely on at-home genetic tests for serious health issues. Getty Images

Genetic tests taken at home have exploded in popularity in recent years.

For a fee, companies like 23andMe will send you detailed information about your ancestry and genetics.

No visit to the doctor is required. All that’s needed is a simple cheek swab.

While the prospect of uncovering this information may seem irresistible to consumers, it’s increasingly important to remain mindful of the limitations of these tests — especially as they continue to grow in popularity.

We know that home genetic tests can give you information on where you came from.

But what are some of the things these tests can’t do for you?

A recent warning letter sent by the Food and Drug Administration (FDA) to genetic testing company Inova Genomics Laboratory illustrates what can happen when genetics companies fail to stay in their lane.

The thrust of the FDA’s warning centered around Inova’s statements that their test could predict patients’ responses to specific medications — a claim not backed up by FDA testing.

“Investigators always work very, very closely with the FDA and have developed some tests that are useful in managing patients who take certain medications,” explained Dr. William Schaffner, professor of preventive medicine in the department of health policy and professor of medicine in the division of infectious diseases at Vanderbilt Medical Center in Tennessee.

“What the FDA is telling this company is that they haven’t shown the data and put it through the approval process,” Schaffner told Healthline.

Dr. Len Horovitz, an internist and pulmonary specialist in private practice in New York and on staff at Weill Cornell Hospital, plus clinical instructor at Weill Cornell Medical College, told Healthline that these home tests just can’t accurately predict what medications a patient should take.

“It’s not in the purview of genetic testing to decide what medications you need, don’t need, or how well they’ll work,” Horovitz said.

“They’ll tell patients about their ancestry and who they might be related to, but they certainly don’t tell you what medications are going to work in terms of antibiotics, blood pressure medications, or cardiac medications,” he said.

What if a take-at-home genetic test could offer personalized diet advice based on your unique genetic makeup?

At least one company, Vitagene, offers a package for $209 that promises “personalized supplements subscription with free DNA kit and genetic based diet, exercise and skin recommendations.”

Researchers have determined this claim isn’t realistic.

A 2018 Stanford University study found that genes can’t predict who might benefit more from a certain diet.

The study did acknowledge there’s great interest in identifying genetic variants that could explain why certain diets work better for certain people.

But after a yearlong study, researchers found no significant interaction between genetics and diet.

On the surface, it might appear that take-at-home genetic tests offer valuable information on the likelihood of developing a disease.

But it’s more complicated than that.

Horovitz says that even if the test reveals a gene with a tendency to develop a certain cancer, people should be cautious about what they infer from this data.

“The fact is that just because you have that gene doesn’t mean you will get the disease, and just because you don’t have that gene doesn’t mean you won’t get the disease,” he explained. “The predictive value of having a certain gene associated with a cancer, for instance, is not clear. It’s not a definite.”

There’s also the fact that, for tumor-based cancers, take-at-home tests aren’t even testing the relevant genome.

“When you do have a certain cancer tumor, then they take that tissue and do genetic testing on that particular tissue — not on your genome, on the genome of the particular tissue,” Horovitz said.

“And that will sometimes dictate which chemotherapy will respond best. That’s certainly the utility of genetic testing in cancer, but as far as saying you’re developing cancer on the basis of these gene tests, that’s guesswork,” he added.

Perhaps the biggest story to hit the news involving genetic tests involves the so-called Golden State Killer.

Police had been investigating the serial killer for decades before finally identifying a suspect. And it was all thanks to take-at-home genetic tests.

No, the accused killer didn’t submit his DNA to a database. But a relative did, and police say that allowed them to identify 72-year-old Joseph James DeAngelo as the likely killer.

Naturally, this raises confidentiality concerns about these genetics companies. After all, these companies are private entities that have been known to hand over data before.

While most people aren’t hiding a dark past of serial murders, there’s still a troubling concern: privacy surrounding genetics as it pertains to insurance companies.

“One thing that concerns patients about these independent tests that they can take and send away are the repeated requests by some of these companies a year or two later to say they could look at this or that, or ask if they can add the information to their data bank,” Horovitz said.

“Many patients are afraid of insurance companies getting a hold of their information for whatever susceptibilities the genetic testing will say they may have. Patients are concerned about their confidentiality,” he said.

The information provided in a take-at-home test isn’t necessarily inaccurate or irresponsible.

Indeed, the ancestry information can be fascinating.

But the tests don’t constitute expert counseling, and patients themselves aren’t experts.

This means that, as always with medical concerns, it’s best to talk to a doctor.

“Ancestry stuff is fun. But if a patient is taking a genetic test specifically to find out, for example whether their cancer treatment or diabetes medication is being administered appropriately, they need to do that in concert with their doctor,” Schaffner explained.

Schaffner says doctors can help determine what tests should be taken, then interpret the results and help counsel the patient moving forward.

This personalized approach is a far cry from the one-size-fits-all approach of take-at-home genetic tests.

“For an untrained patient who doesn’t know medicine, it’s very difficult to try to interpret these laboratory tests in a way that’s actually going to help them,” Schaffner said.