Science Journalism :: Article :: DNA Testing at the Click of a Mouse

Genetic testing is that much easier thanks to DNA kits that can be bought online for as little as $400. What can and should be done with genetic tests, however, was a question scientists explored at a Genome British Columbia public forum held October 22 at Vancouver’s Science World.

The cost of genetic testing has plummeted in recent years, driving a market for DNA sequencing and a natural human curiosity to know more about oneself. But how useful are genetic tests?

“The most powerful steps anybody can take for prevention [of disease] are simple and straightforward: regular exercise, a healthy diet, no smoking,” said Dr. Wylie Burke, director of the University of Washington Centre for Genomics and Healthcare Equity.

Dr. Burke questioned whether a genetic test is as informative as a family history and warned of the risks associated with genetic testing. Burke emphasised that personal healthcare is about more than just your genes, it must take into account your environment and social circumstances.

But according to Dr. Darren Platt, former senior director of research at the genetic-testing company 23andMe, genetic testing is an alternative worth considering as long as it’s considered carefully.

“There is an enormous number of objections [to personal genomics],” says Platt, “Everything from opportunity costs through to ‘it doesn’t tell you the whole story, you’re not going to learn everything.’”

The benefit somebody gets from genetic testing, he says, “is very dependent on their circumstances.”

Genetic testing: how it works

Companies offering genetic testing, such as 23andMe and deCODEme, will sequence portions of your DNA that have been shown to be associated with the risk of developing a disease. The results are presented as a list of traits for which you are at a higher, lower or typical risk of developing. As new discoveries are made, both companies will update you on your risk for these diseases.

It sounds simple—spit in a tube, mail it in, get your disease risk analysed. But the results may not be what you expect.

To illustrate the limitations of genetic testing Mike Spears, director of corporate communications for Genome Alberta, got personal with the audience—he gave out copies of his genetic test results.

Spears’ deCODEme results showed it was unlikely he would have hair at his age. Yet Spears’ long curly hair defied this prediction. Spears’ results also showed he was at a high risk for heroin addiction, leading him to contemplate the stigma he could face if his test results were made public. Spears concluded that genetic test results are not always accurate and can leave people confused.

Potential benefits and risks

Debilitating diseases such as cystic fibrosis and Huntingdon’s disease have been clearly linked to a single defective gene. A genetic test could determine whether the disease will develop in an adult with a family history of Huntingdon’s disease. The fetus of a couple with one affected partner could also be tested for the disease.

Interpreting the results of a genetic test can bring about difficult decisions: should a pregnancy be terminated? How will the knowledge of developing a fatal disease for which there is no cure affect one’s quality of life?

But many believe genetic testing’s popularity will increase despite the many ethical concerns it raises. Since the human genome was sequenced in 2003, personalised healthcare has been touted as the future of medicine. Genetic testing would be the first step in developing a healthcare plan tailored to the individual.

“When we talk about what we should do with [genetic testing], I think we have to be very insistent on a high standard,” said Burke. “Tests that come in to healthcare should come with clear evidence that we know what that test means. In healthcare we have to emphasise clear evidence of clinical, as opposed to personal, value.”

However, the needs of the individual could conflict with those of the healthcare system. For example, a genetic test could identify a small group of people who would benefit the most from a treatment, limiting treatment to this particular group and excluding all others.

Genome B.C., a research organization that receives federal, provincial and private funding and invests in large genomics research projects, said it recognised these ethical ramifications in its position paper on genetic testing. In order for genetic tests to improve the quality of healthcare in B.C., Genome B.C. emphasised the need for regulation.

Dr. Burke’s closing remarks addressed this need. He says that we have to think very carefully about the potential harms and unknowns related to genetic testing.

“Most of the time, [it] will be about making sure we have truth in labelling, so that people know what they’re purchasing,” says Burke. “There’ll be some tests that we think just shouldn’t go forward, even as a consumer product.”

Regardless of the current loose regulatory standards, the temptation to have your DNA sequenced will become more attractive as the price for a genetic test continues to fall.

Now, it’s largely up to the consumer to decide if it’s worth it.