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Risks of online genetic testing

James Randerson

Since the human genome went public, a raft of websites has offered to analyse our DNA -- for a price. But at what cost to our health?

"THIS IS the most important, most wondrous map ever produced by humankind.'' Thus said President Bill Clinton as he welcomed the unveiling of the draft sequence of the human genome — the decoding of the three billion "letters" of DNA in our cells — in March 2000.

It was a day for rousing rhetoric and extravagant claims, and the President was not afraid to bask in the hype. "Humankind is on the verge of gaining immense new power to heal," he said. "Genome science ... will revolutionise the diagnosis, prevention and treatment of most, if not all, human diseases."

Six years on, plenty of companies out there are willing to help you join the revolution. Type "genetic testing" into a search engine and you'll see an array of paid adverts along the sides of the page, offering screening tests, DNA tests, paternity tests, and genealogy tests. It's a thriving business. What's not as clear in the adverts is that the foundations of the business could best be called shallow.

As Mr. Clinton said, sequencing the human genome was a spectacular achievement. But many commentators then glossed over the difficulties in transferring that information into useful medical advances. So far, despite an explosion of research into how our genetic makeup puts us at risk of disease and affects our reaction to drugs or environmental toxins, there have been few concrete changes in the way doctors administer healthcare.

Money for nothing?

But companies looking to cash in by analysing your DNA don't have the same caution. Do your genes make you metabolise coffee and alcohol more quickly than most people? Are you prone to osteoporosis and Alzheimer's in old age? Do you have the potential for sporting greatness? Plenty are willing to answer, if you are prepared to pay.

But are their answers correct? Gail Javitt, at the Genetics and Public Policy Centre, an independent thinktank in Washington, says the human genome project has spawned reams of data on links between genes and disease. We can test for many genes in anyone's DNA. "But the question is really whether the tests are ready for prime time. Do we know enough to say, `yes this test will predict accurately your future risk' of whatever?"

A number of companies say they will. But Ms. Javitt responds: "The answer to the question of whether they are snake oil or not is that there is no way to know... There's no process that most genetic tests have to go through so that an independent evaluator can say, `yes there is data here to support the claims being made'."

But supporters of "direct to consumer" genetic testing — that is, tests unmediated by doctors who might seek to interpret them or hedge the results — say making genetic information available directly to the public is good for us.

"It's really putting you as an individual first," says Fred Ledley of Bentley College near Boston, who founded the genetic testing company mygenome.com. He thinks the future lies in "empowering individuals with access to genetic tests, together with the information and support required to make effective and ethical decisions about how such tests might impact their personal lives."

For example, he says, people who discover they are more prone to a debilitating disease could use that information to decide to buy extra life insurance or opt for early retirement.

There's just one problem: the genetic testing services available at present can't give you that power — though they might aspire to, or insist they can.

Their fallibility was impressively uncovered by a U.S. Government Accountability Office investigation released in July (http://tinyurl.com/gzxur). Over nearly a year, the GAO's investigators anonymously approached four online companies for testing services. They posed as 14 different would-be consumers with a variety of profiles such as age, weight, smoking and exercise habits. In reality, they sent samples of DNA provided from just two people — a 48-year-old man and a nine-month-old girl.

The GAO's damning report shows that the companies — which charged between $89 and $395 for the tests — provided inconsistent results and offered vague and misleading advice to their spoof clients. One offered supposedly tailored nutritional supplements costing up to $1,200 a year; they turned out to be run-of-the-mill multivitamin tablets one could buy from a corner shop for $35 a year.

Failing the test

The GAO was scathing, saying unproven predictions made by the companies "may needlessly alarm consumers into thinking that they have an illness or that they need to buy a costly supplement in order to prevent an illness. Perhaps even more troubling, the test results may falsely assure consumers that they are healthy when this may not be the case."

The report's authors were unremitting. "Despite the implication that these predictions are based on the DNA submitted, none ... contained scientific support to assist the consumer in evaluating their credibility." Genetics experts told the GAO that none of the sites' predictions about links between genes and health — with osteoporosis, heart disease, diabetes, cancer, or cholesterol and toxin metabolism — could be medically proven at present.

Furthermore, one nutritionist flagged the levels of vitamin B6 in some recommended products as "disturbing," while another felt there were high levels of vitamin A and that one site's supplements contained excessive iron, which could remain in the blood and become toxic.

The companies to whom the samples were sent all denied any impropriety.

However Thomas Hamilton, director of the survey and certification group at the U.S. Government's Centre for Medicaid and State Operations, told the science journal Nature that the tests were tantamount to "genetic horoscopes."

The reality is that the labs were never likely to succeed. Even if a particular genetic test has a valid scientific basis, there are other pitfalls, according to Adam Hedgecoe, senior lecturer at the department of sociology at the University of Sussex, and author of The Politics of Personalised Medicine. Even assuming that the lab is competent to detect key DNA variations, the results are never clearcut.

"Any test, even if you run it absolutely correctly, will not give you 100% detection of all positives. There will always be false positives and false negatives," Mr. Hedgecoe says. Those vital caveats are rarely explained in the customer's results.

But if the science is so uncertain, why are the tests available? Currently, the law surrounding genetic testing services is a "regulatory nightmare," says Stuart Hogarth at the department of Public Health and Primary Care at Cambridge University. —

© Guardian Newspapers Limited 2006

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