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Hence the hope being pinned on "pharmacogenetics," a field of medicine that promises to improve health care by allowing doctors to customize medical treatment to suit a person's unique genetic signature. Though experts predict that it could be decades before personalized medicine becomes the norm, research is moving ahead: Last fall, for instance, researchers at Duke University reported that people with a specific genetic variant saw less reduction in LDL, or "bad" cholesterol, when taking statins.
But for some drugs, the future is now. A genetic test recently approved by the FDA should help doctors determine the optimal dose of warfarin (sold as Coumadin), a blood thinner used by 1 million Americans. Determining the right dose is crucial: Too much may result in an increased risk of excessive bleeding, while too little may cause a potentially fatal blood clot. By one estimate, using DNA analysis to prescribe warfarin would prevent about 17,000 strokes and 85,000 serious bleeding incidents.
A small but growing number of doctors and hospitals are also using genetic testing to tailor treatment for these medicines:
- Tamoxifen DNA testing identifies the 8% of women with genetic variants that keep them from metabolizing the breast cancer drug, rendering it ineffective.
- Painkillers like codeine Up to 8% of whites and 2% of Asians and African Americans are poor metabolizers of these drugs and won't get relief from them; for the 1% of "ultrarapid metabolizers," risks include respiratory problems.
- Antidepressants and antipsychotics Some of these drugs are metabolized by the CYP2D6 and CYP2C19 genes. In 2005, the FDA approved a test that looks for these gene variations, and now companies sell consumer versions. But experts advise against using the at-home tests without having your doctor interpret the results, notes Julie Johnson, PharmD, professor of pharmacy and medicine at the University of Florida. The reason: These genes are involved in the metabolization of 25% of all prescription drugs, including several where they're very important. If you misinterpret the results of an at-home test (and mistakenly think you don't have the gene), you might avoid taking one or more drugs you really need.
Jun 21, 2009
Unfortunately, test results aren't always so clear-cut and accurate. Mike Spear, the communications director for a genomic research nonprofit in Alberta, took tests from deCODEme and 23andMe and received some conflicting findings. For instance, the deCODEme test showed a higher-than-average risk for MS, but the 23andMe test said his risk was no higher than that of the average person. The test from deCODEme also had a big check mark next to "male pattern baldness," while the 23andMe test said he was on par with the rest of the population. (Spear, who's 55, still has plenty of hair.) Most surprisingly, both tests told Spear that his risk of asthma was no different from the average person's--even though he already suffers from the disease. His impression: "I'd be careful about basing your life around genetic test results."
Although new genetic research emerges every day, scientists haven't discovered all the genetic variants--or all the SNPs--for common diseases. Green, 54, took two genetic tests, one from 23andMe and the other from Navigenics, and both told him that he had an average risk of cardiac disease. Yet he had undergone triple bypass heart surgery the previous year. As a runner who is not overweight, doesn't smoke, and has low cholesterol, Green suspects there's a genetic cause for his tendency toward blocked arteries--and he chalks up the discrepancy in his test results to the fact that more research is needed to fully understand the genetic causes of cardiac disease.
Another reason to think twice about these tests: The industry is a virtual free-for-all. No single government agency watches the labs performing the tests to ensure that the science behind the tests is even real. Currently, the FDA reviews most other home-use medical tests for safety and effectiveness, but at-home genetic tests don't fall under the agency's territory. Pending legislation would require makers of direct-to-consumer genetic tests to prove that their tests are accurate and properly performed. But right now, "the public's best approach is buyer beware," says Kathy Hudson, PhD, founder and director of the Genetics and Public Policy Center at Johns Hopkins.
Despite these warnings, experts predict that people will be very tempted by the chance to peek into the genetic crystal ball. If you're one of them, heed Katz's reminder: "DNA isn't destiny." And be aware that when it comes to the lifestyle choices that are the greatest predictors of health, your future is in your hands.
Jun 19, 2009
Plenty of companies are eager to meet this demand, selling at-home tests that range in cost from hundreds to thousands of dollars. Some offer tests that have long been available through doctors and genetic counselors--for instance, those that check for BRCA 1 or 2, the genes linked to a small percentage of inherited cases of breast cancer. Newer versions look at your SNPs (pronounced snips, short for "single nucleotide polymorphisms"), the slight variations within DNA that can account for differences in appearance and how we develop genetic diseases. The companies don't predict that you're going to get, say, cancer or macular degeneration. Rather, you get back a report showing the risk you run, compared with the average person. One of the newest entrants into the at-home arena, Navigenics, recently launched its $2,500 HealthCompass test, which looks for markers associated with 23 common conditions--including diabetes, prostate cancer, and Alzheimer's disease--that are "actionable," or able to be prevented or detected early. For an additional $250 per year, subscribers receive personalized updates when relevant genetic research--for instance, the discovery of new SNPs--changes their health outlook.
Health-conscious consumers are clearly enamored with these high-tech tests--they're expected to spend an estimated $6 billion to have their DNA decoded over the next 5 years. But while the business of do-it-yourself DNA testing is booming, experts say this new frontier of medicine isn't ready for prime time. They worry that the field is insufficiently regulated, not all of the tests are reliable, and the information garnered is incomplete and possibly misleading. "Some tests lack adequate scientific evidence to support their use, and the lack of regulation means there's no way for consumers to separate the good from the bad," says Gail Javitt, law and public policy director for the Genetics and Public Policy Center at Johns Hopkins University.
Jun 17, 2009
Critics also note that DNA testing results can be tough to interpret, making it difficult to know when and if you should take action. A Navigenics test told Robert C. Green, MD, PhD, MPH, a professor of neurology, genetics, and epidemiology at Boston University Schools of Medicine and Public Health, that he had a 20% above-average risk of developing multiple sclerosis. But the average risk is 0.3%, and his was just 0.5%. These are both very low risks (3 out of every 1,000 versus 5 out of every 1,000, respectively), yet the results were highlighted in orange, indicating an elevated risk. Green, a geneticist, understood his real risk, but the average person might not, causing needless worry.
And consider the flip side: that someone who tests negative for a gene or is told she's at low risk for developing a dreaded disease becomes less motivated to lead a healthy lifestyle. David Katz, MD, MPH, director of the Prevention Research Center at Yale University School of Medicine, points to a study on premenopausal women given a range of tests to determine their risks of developing heart disease. Half saw scans of their coronary arteries, which were surprisingly healthy. But despite other risks revealed from triglyceride and blood glucose levels, the group that saw its healthy scans did less to follow recommendations to prevent heart disease. "We don't want a single test talking people out of taking care of themselves, and this study suggests that can happen," says Katz.
Jun 15, 2009
At-home genetic tests are all the rage. But can they really calculate your risk of developing life-threatening diseases? Before buying one, read this Prevention special report.
Anna Peterson is only 27, but she's already watched her mother and her aunt develop breast cancer. She also saw her grandmother's eyesight fail from macular degeneration. So Peterson, a graduate student in Ottawa, Ontario, took her health care into her own hands and did what millions of others of all ages are doing: She opted for at-home DNA testing for genetic diseases.
When the results from the $985 test from deCODEme arrived in her e-mail, Peterson felt relief learning that she didn't have an elevated genetic risk for macular degeneration. Yet the test did show a slightly elevated risk for the more common forms of breast cancer. The results, Peterson says, empowered her to make healthier choices. Together with her physician, she'll use that information to advocate for earlier screening for breast cancer--and possibly start getting mammograms at age 30. "Prevention starts with knowing the odds," says Peterson. "I now have the opportunity to make lifestyle changes in my 20s, rather than in my 60s."
Welcome to the brave new world of genetic analysis. Once the exclusive domain of doctors and genetic counselors, DNA testing is now a do-it-yourself proposition, with several dozen companies marketing tests directly to consumers, claiming that they will allow you to understand your genetic profile. The process is surprisingly simple: Buy a test online, swab the inside of your cheek or spit into a test tube to collect a DNA testing sample, and then mail it to the company. In return, you'll receive personalized medical information that purportedly allows you to combat genetic diseases by making informed choices about your health. Bolstering that promise is new research that shows you can actually turn off genes that promote certain diseases by improving your diet and better managing stress.
Jun 13, 2009
(CNN) - DNA is already being used in criminal and paternity tests. But, now genetic testing offers doctors a new way to look for problems of the heart.
For years, Donna Mitchell has tried to lower her cholesterol levels through diet and exercise. Now, she is hoping a cutting-edge genetic test will give her a better picture of her risk for developing heart disease. "I want to live, I like living, I have grandchildren I want to see grow up," said Mitchell. "So, it was a no-brainer for me."
Doctors can test for millions of genetic variations for a number of diseases through a simple cheek swab and blood test. They are looking for inherited traits passed on from relatives.
Mitchell's father died of a heart attack. While some experts say this type of testing needs more development, Mitchell saw potential benefits and so did her doctor. "If you have heart disease and you have one of these heart disease genes then the likelihood that is contributing to your problem is very high," said Dr. Robert Superko, of St. Joseph's Hospital in Atlanta. "And, if it gives you a therapeutic direction, a diet or drug to take then it becomes valuable." Mitchell's testing revealed that she would benefit from taking a cholesterol lowering statin. So in addition to sticking with a healthy diet and daily exercise, she has a new prescription for change. Mitchell tested negative for the so-called heart attack gene.
Jun 11, 2009
You've personalized your ring tones, your screensaver on your laptop, and your stationary. You will soon be able to add your diet to that list of customizable items. However, the process won't be quite as quick or simple as a 10-second download, but the promised benefits should be well worth the extra effort.
Genes and health
You probably have at least a basic understanding of genes, those sequences of DNA that control every structure and process in your body. While the basic set of genes that control one characteristic (say eye color) are organized the same for everyone, little differences in the DNA sequence give one person brown eyes and another blue. Likewise, the genes that control how you utilize a certain vitamin, or metabolize cholesterol level, can vary from one person to the next. Now many of these differences can be measured by simple genetic tests, and the results can be turned into personalized recommendations.
This new science, called nutrigenetics, studies how genes and diet interact. The key word here is "interact." As Rosalynn Gill-Garrison of Sciona, a company that develops genetic tests, points out: "Genes don't determine your fate." Rather these tests give you the information to make optimal choices for your health. A genetic test for , for example, might indicate that you should consume more calcium and vitamin D, rather than saying that your are doomed to dissolve.
Currently several companies are developing consumer-friendly tests for known gene-diet interactions. You can be tested for genetic variations that affect bone health, B-vitaminmetabolism, inflammation status, and utilization of certain antioxidants. The tests are typically done on a swab taken from inside your cheek. The sample is sent to a specialized lab, which analyzes DNA from the cells on the swab. You receive a report on which gene variations you have. A qualified health professional can explain the test results, and make specific diet andsupplement recommendations to optimize your health.
What about genetic testing for weight loss?
The $64,000 question is this: When will a genetic test help me to lose weight? Unfortunately, this test does not yet exist. In fact, it is unlikely that just one test will ever answer that question. Registered dietitians Ruth DeBusk and Yael Joffe, co-authors of "It's Not Just Your Genes,"write that genes may someday tell us which weight-loss diet is best, why one person burns more calories than another, and (even better) how to use gene technology to promote . But they caution that hundreds of genes could impact weight. Deciding which of those hundreds are worth studying will be a daunting task.
The future of personalized diets
Diet and nutrition advice in the future will be increasingly personalized. As genetic researchers identify more gene-diet interactions, dozens of personalized recommendations for diet will be possible. Hopefully, before too long, weight control will also be part of that mix of genetic tests. In the meantime, the first generation of nutrigenetic tests is available for several important diet-gene interactions. One-size-fits-all diet advice will be a thing of the past.
Jun 9, 2009
Internet marketers claim that a genetic test can give you a personalized diet. Are they advertising cutting-edge science or a high-tech horoscope?By Laura Hercher When President Bill Clinton stood in the East Room of the White House on June 26, 2000, and hailed the completion of the Human Genome Project, calling its results “the most important, most wondrous map ever produced by humankind,” he was not looking to inaugurate an era of high-tech snake oil sales. Yet less than a decade later Web-based purveyors of genetic tests and dietary supplements are hawking nutritional genetics, or nutrigenetics, with claims that it can look at an individual’s genetic information to figure out what that person should eat to promote stronger bones, shinier hair and other trappings of good health. So far, though, hyperbole has outpaced promise. This nascent field provides a cautionary tale of how commerce often races ahead of science: the commercialization of gene detection technology has occurred before scientists have developed an adequate understanding of how particular genes contribute to health and disease.Information derived from sequencing the DNA code in every human chromosome is gradually enabling scientists to create tests and treatments that have the potential to prevent, diagnose, ameliorate and perhaps even cure disease. It is also paving the way for “personalized medicine,” which is based on the recognition that genetic differences among individuals can explain why one person’s body reacts differently than another’s to food, drugs, sun, exercise, allergens or other stimuli. In an ideal world, a genetic test would reveal which medication or other therapy would work best and produce the fewest side effects in a given individual. And investigators are now beginning to create such tests. One milestone occurred this past summer, when the Food and Drug Administration approved the first genetic test to help a patient gauge the best dosage for a blood-thinning drug called warfarin. The test is certain to be followed by scores of others that attempt to better match drug to patient.
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Secondo uno studio olandese e uno americano, chi ha sofferto di depressione ha due volte e mezzo più probabilità degli altri di contrarre il morbo.
Tuttavia, i ricercatori olandesi, hanno precisato che sono necessarie altre ricerche per comprendere appieno il legame tra la malattia D Alzheimer e la depressione: “Non sappiamo ancora se la depressione contribuisce allo sviluppo dell’Alzheimer – hanno confessato – o se un altro fattore sconosciuto causi sia la depressione che la demenza senile.” Dal canto loro, gli scienziati americani sottolineano comunque che la depressione è un fattore di rischio per l’Alzheimer ma non un sintomo precoce del morbo.
In altre parole, non tutti i depressi si ammaleranno. Insomma, ancorché non definitivi, i risultati aiuteranno comunque a capire di più i meccanismi del morbo e creare nuove prospettive di ricerca.
Articolo pubblicato sul quotidiano “City” in data 9 Aprile 2008.