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December 4th, 2008
06:51 PM ET

Genetic testing

Elizabeth Cohen
CNN Medical Correspondent

It sounds like the medical equivalent of a crystal ball: A single test that helps tell you your chances of developing Parkinson’s disease, prostate cancer, diabetes, alcoholism, obesity, Lou Gehrig’s disease, and more than 75 other diseases and conditions . Wow, I thought, I’ve discovered the holy grail of health care.

The genetic analysis is offered by a company called 23andMe – here’s the section that lists all the things they test for. You just spit into a test tube (don’t worry, you won’t miss; they give you a funnel), mail it in, and pay $399 for a genetic analysis of dozens of diseases that ends up on a secure Web site, which you can peruse at your leisure. The site quotes a satisfied customer: “I thought how fascinating if I could know more about my future. I should be aware for myself. For my children. If there’s something that I could prevent for the future…why not learn? Why not help myself?”

I ran into this Web site while researching a story this week on genetic tests being offered online. The question that keeps coming up in my mind is this: What do you get for your $400? Do you find out for sure that you’re destined to get, say, glaucoma? That you’re more likely than most people to get it? Way more likely or just a little more likely?

“I can’t figure out what you get for the $400,” I said to Brian Naughton, the Founding R&D Architect at 23andMe (yes, that really is his title, and the company name comes from the fact that we all have 23 pairs of chromosomes). “For example, if I get your test and it tells me I have the worst possible heart attack genes, what chance do I have of having a heart attack?”

Naughton consulted his notes: If the test shows you have the worst possible genes, you have a 21 percent chance of having a heart attack at some point in your life.

Okay, and the average person? What’s his or her risk of having a heart attack at some point?
18 percent. Oh. So for $400 I get to find out that I have a 21 percent chance of having a heart attack instead of the usual 18 percent? How are these three percentage points helpful to me?

I put that question to Linda Avey, the co-founder of 23andMe. “I don’t think heart attack is really the best category for you to look at,” she said. “There are many genes involved in whether or not you’ll have a heart attack. We’re just testing for one of them.”
Oh again.
Okay, I said to Naughton. Give me your best shot. You test for dozens of diseases. Give me the one that would really make it worth it for me to send you $400. Parkinson’s, he told me. If you have an extremely unusual genetic variation, you have a 59 percent chance of getting Parkinson’s sometime in your life rather than the usual 1-2 percent chance of getting the disease. Wow, a 59 percent risk – that’s high. And if I test positive for this gene, what can I do? “I’d drink more caffeine,” Naughton said. “A study showed that people who drink more caffeine are less likely to get Parkinson’s.”

So I put this question to two neurologists: If a patient came to you who had this “Parkinson’s gene,” would you tell them to start drinking more caffeine? Both said absolutely not. “Caffeine comes with higher risk of hypertension and cardiac arrhythmia,” said Dr. Milind Kothari, vice-chair of the Department of Neurology at the Penn State College of Medicine.

So what’s the bottom line of all this? According to Mark Bouzyk, director of the Center for Medical Genomics, it’s one thing to get a genetic test when you have a specific reason to do so. If your mother and sister have breast cancer and you’re a Jew of Eastern European ancestry, you have a relatively good chance of carrying the bad gene, and knowing if you do or don’t can help you make important health decisions.

But without a specific reason, he says you should be careful when you go fishing into your DNA for information about dozens of diseases. You might end up wasting a lot of money. Or, even worse, you might find you have a high chance of getting a horrible disease – when there’s not much you can do about it.

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Filed under: Elizabeth Cohen • Medical News
soundoff (3 Responses)
  1. Pearl Pfiester

    I believe the author from her media perspective skewed the reality and usefulness of genetics testing to "make a story." Many genes make a protein and the process is rather complex so the "one-gene association" dream to a disease is not valid. The fact someone may have mutation(s) or chromosomal instability (microsatellites e.g.) present (person can be mosaic too) does give one a higher probability to disease. As for PD, they are still trying to find the exact candidate gene ex. p.R1141C (I just read a paper from the European Human Genetics Journal published 2008).

    Cancer is something that worries people; CANCER IS GENETIC and can be PREVENTED by positive lifestyles.

    Genetics testing informs people's disease susceptibility. This can play a role for people that choose to procreate; they can avoid passing the sex-linked genes to offspring for example. People can make future choices based on their screening or family history to decrease the probability. Time and time again, it's unfortunate that the media does not report science accurately; only a partial story comes out usually.

    I don't pretend to know everything about genetics but I feel I have a better understanding than most people. I would love to talk about genetics to the author sometime.

    December 5, 2008 at 3:50 am |
  2. A. M. from NY

    I think that we should use genetic testing in more constructive ways. Instead of trying to determine the future, we can prevent many genetic diseases by testing the compatability of a couple before they have children. A private Brooklyn, NY based non-profit began testing for many diseases years ago, after the founders lost a few children to the disease. They ahve almost obliterated tay-sacks and other devestating genetic diseases.

    December 5, 2008 at 12:31 am |
  3. Tammy, Berwick. LA

    I've had several health professionals tell me over the years that I am a genetic medical nightmare. Having sad that, they have also said over and over again that I could control what happened to me regardless of the history. I used to want to be tested for juvenile diabetes genetics because the disease killed my mom at 53. Well, without genetic testing I came up in a routine check as a pre-diabetic over a year ago and knew I didn't want to die like my mom did. I have worked harder than I ever have in my life, and I beat it. I will for the rest of my life have to continue to beat it. Obviously, the genetics are there, but the rest matters more I discovered. My doctor and I are overly vigilant. And I am proof that the worst genetics in the world don't mean an automatic death sentence. I wouldn't waste the money on testing. I would, however, spend the money on a good medical history, work up, and doctor who is just as aggressive and proactive in wanting to prevent this disease as I am.

    December 4, 2008 at 11:12 pm |