Family history trumps genetic tests

Genetic tests have the aura of being scientific. But the old-fashioned family history appears to be more accurate and much less expensive.

A Cleveland Clinic researcher recruited 44 people to assess their risk of cancer by either preparing a  family history or relying  on a genetic test. Both indicated that about 40 percent had above-average risk – but picked the same people half the time. The genetic test did not identify the nine people who had a significant family history of colon cancer.

Likewise, researchers collected 101 genetic variants that had been tied statistically to heart disease in genome studies. They assessed and followed 19,000 women for 12 years to attempt to forecast disease. They concluded that the family history was a better predictor.

One reason family histories can be more accurate is that environment is a powerful influence on health. Family members generally share a common background, so the history reflects how shared genes expressed themselves in a given situation.

Family members often take important genetic information to their graves inadvertently without sharing it with relatives. According to one study, about 1 in 5 dying cancer patients could have shared important information with relatives through genetic counselors regarding the heritability of their conditions. In some instances, they could have left behind blood and tissue samples for future DNA testing. That would be a valuable legacy. (Genetic counselors help people understand their risk for genetic conditions. The National Society of Genetic Counselors website, www.nsge.org, lists them by zip code.)

Less than one-third of U.S. families have documented a health history, and many physicians are not particularly insistent that they have one. The U.S. surgeon general has established a website – https://familyhistory.hhs.gov – to help families create a history and share it with other relatives.

Many scientists have concluded that DTC genetic tests offer very little value. They say the increased risk posed by any given gene is so small that it is not information worth acting on. The best predictors of disease and death are already well known: age, gender, family history, health behavior and biomarkers such as blood pressure, blood glucose and cholesterol.

An international research consortium identified 18 new gene sites associated with obesity and 13 others tied to fat distribution in the body in 2010. The two studies, which one of the researchers called “exciting,” will not have much immediate clinical impact.

Michael Jensen, an obesity expert at the Mayo Clinic, told The Wall Street Journal, “If you just ask people whether their parents were obese or not, the ability to predict whether a person is going to be obese is better” than by examining the identified genes.

Dissecting your genome at the drug store

Regardless of their validity, personal-health blueprints are in great demand.

In a poll taken right after the Walgreens recall, nearly 3 out of 4 said drugstores should sell genetic testing kits, compared with only about 1 in 4 doctors.

People appear willing to pay a lot of money even for imperfect or marginal genetic information about themselves. Tufts Medical Center researchers posed scenarios to about 1,500 people based on disease, risk of getting the disease and test accuracy. Most said they would be tested – from about 70 percent  for a flawed test for Alzheimer’s disease and 10 percent average risk, to nearly 9 out of 10 for a perfectly accurate prostate-cancer test and a 25 percent average risk. People were willing to pay an average of $320 for an imperfect arthritis test, $622 for a hypothetically accurate prostate test.

Four of 5 Americans support a national study of how genes are affected by health behavior and the environment. About 60 percent said they would supply their DNA.

Younger adults are especially interested in genetic information. About half believe that genes play an equal role in health to lifestyle habits. Those with riskier health behavior tend to say genetics has a more pronounced effect, perhaps as a rationalization for bad habits. Those with a family history of disease also place a greater value on genetic information. In reality, genetic markers, on average, account for only about 10 percent of the overall risk of acquiring a disease.

A study in the New England Journal of Medicine attempted to determine how spooked people would be by the results of DTC genetic tests. Researchers assessed the anxiety levels of more than 2,000 who used the tests to analyze their probability of getting any of 22 different diseases. The result: Nine out of 10 were unfazed. Another result: Hardly any of them changed their health habits after getting the results. The implication was that the test was harmless psychologically and ineffective in making a difference in anyone’s life. According to the researchers, DTC tests are “underpowered” with data.

A separate study of genetic-test takers found that about 1 in 4 slightly altered their lifestyles based on the results. About one-third shared the results with their physicians, many of whom did not know what to make of the information.

With genetic tests, consumers seem to be in one of two categories: the fatalists who consider inherited  risk to be destiny that cannot be altered by changes in behavior, and those who believe they can make a difference with lifestyle changes.

A $1,000 genome in a day

Life Technologies Corp. has unveiled a device designed to sequence an entire genome in one day for $1,000.

The $1,000 benchmark is an important one. Personalized medicine has the ability to guide prevention and illness treatment, and allow drug companies to develop more targeted pharmacological therapies.

The good news is that the price is dropping so fast that the direct-to-consumer market may well blow away. That is good news because those “kits” do not tell you much.

Legitimate genetic testing often is lumped with over-the-counter drugstore tests.

Medical-device manufacturers sell test kits to hospitals, clinics and laboratories. The Food and Drug Administration regulates these products, whose results are interpreted by trained health-care providers. Laboratories also develop their own genetic tests, which are overseen by the Centers for Medicare and Medicaid Services.

By contrast, Walgreens postponed selling the Pathway Genomics genetic test in May 2010 after the FDA challenged its legality. The government appears to be deciding whether the retail products are medical devices, which would require regulation, or simply consumer information.

Direct-to-consumer (DTC) genetic tests are about probability, not certainty. Environment, behavior and luck conspire to determine whether genes will express themselves. In other words, someone who eats right and exercises may well offset a genetic propensity to gain weight.

At its best, in-home genetic testing empowers patients to manage their health and assess personal risks. However, DTC testing is predictive, not diagnostic. It attempts to assess susceptibility to, and probability of, disease – not its presence. The worst-case scenario: Consumers can easily conclude that a disease mentioned in the DTC profile will occur in the future – regardless of its statistical probability.

A Government Accountability Office (GAO) investigation of four companies found misleading test results and “egregious examples of deceptive marketing.” Federal officials sent real donors’ samples to four companies and posed as fictitious customers to inquire about results. According to the GAO, the companies produced different results for identical samples and told customers they had low risks for diseases they already had.

A 2006 report argued that “the potential harms (of DTC genetic tests) outweigh the potential benefits.” A Federal Trade Commission “facts for consumers” bulletin cautions that “having a particular gene doesn’t necessarily mean that a disease will develop; not having a particular gene doesn’t necessarily mean the disease will not.”

Australian journalist Ray Moynihan was far blunter in an article titled: “Beware the fortune tellers peddling genetic tests.”

He said, “For anyone concerned about the creeping medicalisation of life, the marketplace for genetic testing is one of the last frontiers, where apparently harmless technology can help mutate healthy people into fearful patients, their personhood redefined by multiple genetic predispositions for disease and early death.”