Genetic Tests and Gene Editing: The Reports are Exaggerated

FROM THE LECTURE SERIES: THE SKEPTIC'S GUIDE TO HEALTH, MEDICINE, AND THE MEDIA

By Roy Benaroch, M.D., Emory University

When reporting on genetic testing and gene editing, the media will often tell you about the caveats and the drawbacks of the testing. But some stories really go overboard, exaggerating the benefits—or the dangers—to an almost ridiculous degree.

3-D illustration of DNA double helix molecules and chromosomes.
Genetic tests can reveal that changes can be mutations or more normal variations called polymorphisms. (Image: nobeastsofierce/Shutterstock)

Mutations or Polymorphisms?

From Jacksonville’s News4Jax came a story titled “The Tell-All-Test Could Save Your Life.” The story begins, “If you’re feeling tired or sick all the time, there’s a tell-all-test that could help identify why….” Further down, the author continues with the same theme:

Like many of you reading this, I am always tired and I get sick way more than I think I should. I have chalked this up to having a 3-year-old and working very early hours on The Morning Show. While those may add to the problem, it turns out that I have been living with a very common gene mutation, but never knew it.

The first problem is the word “mutation”. It is not the right word to have been used in this context. In medical terms, the test isn’t looking for rare, new mutations, but the far more common appearance of variations among the genes we all carry. They’re technically called “polymorphisms”. It’s those polymorphisms that make us different, by changing our eye color or how well we metabolize alcohol.

All of these variations, which have been carried on in our genes for thousands of generations, aren’t really mutations anymore. But that word, ‘mutation’, connotes something bad and scary, and unscrupulous marketers sometimes use that term to frighten people.

So, the author discovered from testing that she had a variation—what she called a mutation—in a gene called MTHFR. She then discussed that a chiropractor explained that this variation was making her sick. He said:

The MTHFR gene is a big deal … You can have two people in a room and a virus enters it. One person gets sick and the other doesn’t. The one who gets sick very likely has a mutation of the MTHFR gene.

But it’s not true. About 60%-70% of us carry what’s considered a variation of the MTHFR gene, meaning that variations are so common, they’re essentially normal, too. This MTHFR story is just one example of a gene whose variants were once thought to contribute to disease.

This is a transcript from the video series The Skeptic’s Guide to Health, Medicine, and the Media. Watch it now, on The Great Courses Plus.

Gene Testing Errors

Still, there are plenty of companies offering the testing, and plenty of people cashing in on the hype. Forbes magazine covered this issue in a 2016 article entitles “How Your Genetic Sequence Can Be Exploited by the Supplement Industry.” Testing of the MTHFR and other genes is sometimes used as a guide, it’s claimed, for special vitamins or other supplements. Ironically, the article points out, some of these supplements may themselves lead to an increased risk of health problems like cancer.

And one final caveat: In a study published in the prestigious journal Nature, researchers found that 40% of reported variants were false negatives. So, these tests are often flat out wrong.

Learn more about the misconceptions about genetics and the Punnett squares.

Genetic Manipulation for Removing Diseases

But media is also now reporting about genetic manipulation: technology that can directly change a person’s genetic code. A 2017 Los Angeles Times, August 2017 headline read “In a First, Scientists Rid Human Embryos of a Potentially Fatal Gene Mutation by Editing Their DNA.” The story is about a procedure reported in the journal Nature: “The first time that scientists have altered the human genome to erase a disease-causing mutation not only from the DNA of the primary subject but from the genes of his or her progeny as well.”

The goal would be to fix disease-causing genes by permanently removing them from a genetic lineage. That would be incredible if we could permanently eradicate a disease. But as the article points out, with such power comes the potential for less high-minded aspirations: “… others fret that the technique may be used for less noble purposes, such as creating designer babies with desired traits like green eyes, an athletic build, or an aptitude for mathematics.”

Learn more about the human characteristics that aren’t governed by a single gene.

Designer Babies? Don’t Hold Your Breath

A digital image of a baby crawling out of a test tube.
The creation of designer babies is a commonly feared result of gene editing. (Image: gualtiero boffi/Shutterstock)

Now, as the article points out, in the US, gene editing is forbidden outside of a research setting. But technology has a way of crossing borders and escaping from labs. Some sources address the implications of this kind of tinkering before it becomes widespread. The New York Times did a good job providing some reassurance in their article: “Gene Editing for ‘Designer Babies’? Highly Unlikely, Scientists Say.” Quoting from the article:

Here is what science is highly unlikely to be able to do: genetically predestine a child’s Ivy League acceptance letter, front-load a kid with Stephen Colbert’s one-liners, or bake Beyoncé’s vocal range into a baby. That’s because none of those talents arise from a single gene mutation, or even from an easily identifiable number of genes. Most human traits are nowhere near that simple.

Exactly. While there are thousands of examples of diseases that can be linked to a single genetic change, there are far more diseases and characteristics that are related to multiple genes, each contributing something to the final outcome. Fears about designer babies, to quote The New York Times, “are closer to science fiction than they are to science.”

Common Questions about Genetic Testing and Gene Editing

Q. What do genetic tests look for?

Genetic tests are often talked about as looking for mutations. However, most genetic tests are searching for normal gene variations called ‘polymorphism’. This are the subtle variations in genes that are decide things from hair color to how well you can metabolize alcohol.

Q. What is the accuracy of genetic testing?

In a study published in the prestigious journal Nature, researchers found that 40% of reported variants in genetic testing were false negatives. So, it is clear that the results of genetic testing are often wrong.

Q. What is genetic manipulation?

Genetic manipulation refers to technology that enables you to edit the genetic code of an individual. Gene editing can help remove diseases not only from the individual but from the genetic lineage of that individual.

Q. Are ‘designer babies’ likely in the near future?

According to most scientists, it is highly unlikely that science will be able to create a designer baby by genetic manipulation. Most human traits, especially talents, are so complex, and rise from an effect of so many different genes, that it would be virtually impossible to create a specific set of characteristics.

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Unpacking Human Behavior: The Gene-Environment Correlation
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