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Testing the Genome

With Knowledge Comes Power … or Paranoia

By Boonsri Dickinson
Dec 14, 2007 6:00 AMNov 12, 2019 5:06 AM


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Beginning this spring, the genomic start-up company Navigenics will sell spit kits for $2,500 to those curious enough to learn more about their DNA. Along with results telling you the genetic disorders you can look forward to, you receive advice on how to reduce your chances of developing up to 20 diseases and an offer of genetic counseling sessions.

But paying $2,500 to find out that you are predisposed to Alzheimer’s, which has no cure and few treatment options, could seem like a raw deal. That’s why it seemed a bit unfair when, after spending millions to have his entire genome sequenced, Craig Venter found out that he has the apolipoprotein E gene, predisposing him to Alzheimer’s. But Venter is unfazed. In fact, he has no regrets about the finding. Instead he is trying to do something about it—hoping to push back the onset of the disease by taking drugs, changing his diet, and exercising.

“I don’t feel like I have the threat of Alzheimer’s disease hanging over my future,” says Venter. The only person in his family since the early 16th century to have dementia was his great-grandmother, so the familial type of Alzheimer’s, which is responsible for about 3 percent of cases, is not likely. It’s the type called sporadic Alzheimer’s disease that Venter is trying to avoid; it causes 97 percent of cases.

For those of us lucky enough to reach age 85, half of us will suffer Alzheimer’s. By 2050, one in 85 people around the world will suffer from it—four times the current number.

Venter is taking proactive measures. He now takes statins, cholesterol-lowering drugs that are the top-selling medications in the United States, because he has heard from friends in the pharmaceutical industry that statins could prevent the onset of Alzheimer’s. Statins reduce the amount of cholesterol the liver produces by blocking the enzyme needed to make it. But it’s unclear if statins have an effect on cholesterol in the brain.

Jerome Goldstein, director of the San Francisco Alzheimer’s and Dementia Clinic, isn’t convinced they are all that effective. It’s true that “bad” cholesterol impairs your brain function, Goldstein says, but without cholesterol in your brain, you don’t form nerves. He prescribes statins to treat his patients with Alzheimer’s disease because it might possibly delay the disease’s progression. Giulio M. Pasinetti, director of the Center of Excellence for Research in Alzheimer’s Disease at the Mount Sinai School of Medicine in New York, is more adamant about statins’ lack of effectiveness, saying that large-scale clinical studies have proved that they don’t have any effect on the cholesterol in the brain.

“Thank god statins don’t change it,” says Pasinetti. "You don’t want to interfere with the fine-tuned mechanism associated with the function of the brain by changing the cholesterol level in the brain.”

Pasinetti’s research is based on more holistic, natural treatments. Pasinetti has shown that polyphenols in red wine reduce cognitive decline—and may prevent it—in mice genetically altered to develop Alzheimer’s; he hopes to prescribe red wine (and grape juice varieties) to humans in the future. Pasinetti also suggests that exercising regularly, restricting caloric intake, and choosing healthy nutrients will go a long way to prevent Alzheimer’s disease.

Goldstein agrees. “There are other things you can do that will prolong life. Walk a mile a day. Solve crossword puzzles. Read instead of watching TV. Take certain vitamins. Take good health measures. Control cholesterol.”

Although no one agrees just how to deal with the knowledge that one is likely to get Alzheimer’s, millions of dollars is spent on research into the disease each year. With personal genetic testing ready to take off, that’s good news for the many people who will be learning their genetic predispositions.

See the related magazine story: 9. The Genome Turns Personal

Go to next story: 10. T. Rex Time Machine

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