April 29, 2010 -- Do you really want to know all of the information encoded in your genes? A thought-provoking new study shows why you might -- and why you might not.
It's not science fiction. It now costs less than $10,000 to learn your own personal genome. Soon it will cost no more than $1,000. What might you learn? Ask Stephen Quake, PhD, a Stanford University bioengineer.
Recently, Quake and colleagues showed that a whole human genome -- his own -- could be unraveled by a single technician using a single machine.
When a 19-year-old relative died suddenly in his sleep, Quake began to wonder whether the information he collected could tell him whether he risked the same fate. He took his genome to cardiologist Euan Ashley, MD, who runs Stanford's hypertrophic cardiomyopathy center.
"This made me start thinking about what doctors are supposed to do when a patient walks into your office, shows you his whole genome, and asks, 'What is in my crystal ball?'" Ashley tells WebMD. "It's a challenge. Lots of people have looked at human genomes, but nobody had ever looked at a single patient before."
Ashley and Quake assembled a large group of Stanford's top researchers. The group pored over all available information on genetic risk and then evaluated millions of the variations in Quake's genetic code.
In the end, it turns out that Quake carries three gene variants linked to sudden cardiac death. Genetic analysis shows he's at increased risk for heart attack, clogged arteries, type 2 diabetes, and some cancers.
Does this mean Quake is particularly unlucky? No. Because of the frequency of risk genes in the population, every single person who looks into their genome will find that they carry risk genes for more than one serious or deadly disease.
"It is all bad news," Quake tells WebMD. "After all, there is no genetic basis for happiness or athleticism. It's all about things that make you uncomfortable and ill. You have to have a strong stomach."
While it isn't what you'd call really good news, Quake did learn a number of helpful things. He's genetically more likely to respond to low doses of cholesterol-lowering drugs with a lower risk of side effects (in fact, he's begun taking the drugs even though he's only 40).
And should he ever need the drugs, Quake learned that he's less likely to respond to the blood-thinning drug Plavix than to alternative drugs, and he would need a lower starting dose of warfarin.
Ethical Issues Plague Whole-Genome Test
While there's always bad news from whole-genome sequencing, the fact that a person is at higher risk of a particular disease does not mean they're destined to suffer from it.
"The genome is not destiny. Many things have a chance to influence the outcomes," Quake notes. "There is a genetic component to risk, but there is an environmental component, too. For the vast majority of things about your health, your lifestyle choices and the environment you live in make equal contributions."
Understanding genetic risk isn't easy. Even scientists like Quake need counseling to put personal genetic knowledge into perspective. And right now there are no requirements for companies that offer gene sequencing to provide such counseling, warns Arthur Caplan, PhD, director of the Center for Bioethics at the University of Pennsylvania.
"Amidst all the genome hype, people ignore environmental causes," Caplan tells WebMD. "They say, 'I don't have the gene for breast cancer, but smoke three packs of cigarettes a day and never exercise.' Not having a risk gene for a disease is false security, and having one is not a death sentence. All this has to be explained."
That could be a big problem. In an editorial published alongside their study in the April 30 online issue of The Lancet, Ashley and several of his colleagues note that the average person will discover he or she has about 100 genetic risks.
"Even if [counseling on] that information averaged only three minutes per disorder, this process would take more than five hours of direct patient contact, after many hours of background research," they calculate.
And there are only about 2,500 trained genetic counselors and 1,100 clinical geneticists in North America, all now busy with other work.
And there's another big issue: What do you tell your close relatives, who share many of your genes?
"Finding out about your own risks leads to information about your relatives, which you may try to tell them whether they need to know or not," Caplan says. "If you show up at Thanksgiving screeching about the risk for Alzheimer's you found out you have, your relatives may say, 'Hey, I didn't want to know that."
So who should get their genomes deciphered? Caplan says those who think they are interested should ask themselves some serious questions:
- Do I have a history of any genetic diseases in my family?
- If I got information I could not do anything about, would I still want to know?
- If I get information about risk and it implicates others, how will I handle it?
- Are the people I'm seeking testing from reliable?
- Am I willing to change my lifestyle to reduce the risks I learn about?
And Caplan has one more piece of advice.
"If you're just looking to learn about your overall risk, instead of getting in the car and heading over to the genetic testing facility, you may want to jog over," he says. "And while you're jogging, think about what you really are going to do to reduce your lifetime risk of disease, and jog back."