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MarionFranckW

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DNA holds on to its mystery even as we try to decode it

By From page A15 | July 21, 2013

When I was offered a free gene test kit from a company called 23andMe, I signed up as a lark. I was curious to learn about my ancestors, and I didn’t pay attention to the fact that I’d be receiving health data, too. When it arrived via a web site, the little padlock around my Alzheimer’s risk brought me up short.

Should I look?

Instead of clicking, I headed for the library where I found a book titled “Here is a Human Being,” published in 2010 with the subtitle, “At the Dawn of Personal Genomics.”

The author, Misha Angrist, was one of the first to have his entire genome sequenced. Although he describes himself as a pretty anxious guy, he has a strong background in genetics and was comfortable making his genome public.

However, most of his book is about other people: scientists and entrepreneurs who have been trying to decode DNA and market the decoding. In addition, Angrist tells stories of first-time users like himself.

It turns out that I’m far from alone in being nervous about my Alzheimer’s status. The APOE4 gene correlates with higher-than-average odds of getting Alzheimer’s, especially if you receive copies from both parents. No lesser person than James Watson, co-discoverer of the structure of DNA and one of the first to have his genome sequenced, chose not to know whether he carries APOE4.

Unfortunately, another scientist was able to deduce Watson’s APOE4 status from studying genes around what Watson had put in the public domain. Angrist doesn’t reveal Watson’s results, but he observes that nowadays steps you take toward privacy don’t necessarily succeed.

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The company I used, 23andMe, does not decode your entire genome. Rather, it studies something less expensive: about one million individual points on the genome called single-nucleotide polymorphisms (SNPs), biological markers that offer clues to your DNA.

When 23andMe utilizes a marker for disease, how much is known about that marker? How does it compare to other markers they don’t test for? For each disease, does it take one marker or many to know your risk?

These are important questions.

23andMe cites numerous research studies from all over, but it is difficult for a non-scientist like me to weigh the importance of one study over another.

In addition, scientists agree that environment plays a huge role in whether or not you develop a disease. If, for example, I have a susceptibility marker for diabetes but I lead an extremely healthy lifestyle and eat a good diet, what are my chances of getting the disease? If my uncle had diabetes, am I more likely to get it?

Some day aggregated data from millions of people will provide answers. 23andMe asks customers to fill out questionnaires that will contribute to that kind of research, but how much should I trust what I receive right now? How well do I understand it?

Angrist writes, “I knew enough about statistics to know that having a risk ratio go from 1 to 1.6 or even 2 meant my absolute risk had only risen from, say, 1 in 10,000 to 2 in 10,000.”

I didn’t know that. Most of the risk numbers I received from 23andMe compare my risk to average risk. This is confusing. Do I have to investigate each marker further to understand my absolute risk?

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People react unpredictably to news about their genes. Some of us are great at denial or letting go of worries, while others are inclined to make mountains out of mole hills. When it comes to health, I’m in the latter group.

Angrist cites one scientist, Harvard neurologist Robert Green, who discovered that people who learn that they are at higher-than-average risk for serious disease become distressed at first but then return to normal, with no regrets about having obtained the information.

Really? I’d like to know more about this.

Even if people remain calm in the face of bad health news, will they overload the medical system as they investigate possible future problems? Should we anticipate a new flood of medical spending?

DNA-related companies are proliferating and information about genes is coming at us like a tidal wave. For example, the director of the National Institutes of Health, Dr. Francis Collins, has predicted that complete sequencing of newborns “is not far away.”

How will this affect a child’s future? The brave new world of genetics could change our society as much as cell phones or the internet.

But interpretation of results is in its infancy. And we don’t know enough about human response to receiving this data, which my own psyche says could be painful.

In his last pages, Angrist reminds us that the devil is in the details. He gives the example of a gene for type 2 diabetes which, if you receive it from your father, puts you in danger of the disease, but if you receive it from your mother, protects. It will take huge population studies to tease out the truth of such things; those of us who get genetic information now don’t receive much that is comprehensive and verified.

I still haven’t looked at my Alzheimer’s results.
— Marion Franck lives in Davis with her family. Reach her at [email protected]

Marion Franck

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