Harvard geneticist George Church is convinced everyone should have his or her genomes sequenced. Such tests would reveal the rare diseases and handful of cancers that we’re all at some risk for, even if our family members don’t have them.
But many others in the field say we still don’t know enough about genetics to justify getting the test done.
“I think the evidence is not there yet for that balance to be tilted more toward population screening,” says Muin Khoury, director of the office of public health genomics at the Centers for Disease Control and Prevention.
The first human genome sequence was completed in draft form in 2000 for $3 billion. The cost has come down so much — to about $1,000 — that it’s now conceivable for people to get all their genetic information read out without help from insurance, which usually won’t cover the procedure.
The problem is it’s still easier to get the data than to know what to do with it.
Right now, Khoury says, studies reveal variations in the genome that might not cause problems but could lead to unnecessary medical tests, anxiety and treatments.
“You’re going to find a lot of things you don’t know what to do with,” Khoury says. “Most of it is noise.”
Hope vs. false hope
Genetic sequencing can help solve diagnostic mysteries, finding causes for rare diseases. It also can be incredibly useful for some cancer patients, finding therapies their doctors wouldn’t otherwise have considered.
That approach saved Eric Dishman’s life.
Dishman was diagnosed with kidney cancer at 19, and struggled for 23 years on various treatments. Five years ago he was out of options and near death when he got his own and his tumor’s genomes sequenced. The tests revealed that his cancer had a mutation commonly found in pancreatic tumors. Treatment with a medication targeted for pancreatic cancer got him healthy enough for a kidney transplant, and he’s now cancer-free.
But Dishman concedes that he was very lucky to have such a useful result. And he worries that people will build unrealistic expectations from the idea that gene sequences inevitably lead to successful treatments.
“False hope is not a good thing,” he says. “I lived through decades of ‘This is the drug that’s going to cure your cancer,’ and then they put me on it and it almost killed me.”
Dishman now heads President Obama’s Precision Medicine Initiative, which plans to sequence the genomes of 1 million Americans over the next few years and then follow them over time to see how genes interact with their physical environment, socioeconomic status, body chemistry and life history.
He’s hopeful the research eventually will justify screening for everyone.
Knowing can be a bad thing
Church, who was the fourth person in the world to have his genome sequenced, says that day already is here. His own genome did not save him from an avoidable cancer or midlife health crisis — but for somewhere between two and 20 people per thousand, it might, he says.
“What’s the justification for waiting?” he asks.
Church argues that we all do many things for the benefit of equally small fractions of people. Lottery tickets only pay off one time in 300 million, in some cases, but plenty of people voluntarily pay for them, he says.
If people don’t want to know about their risk for conditions they can’t do anything about — such as Alzheimer’s — they can ask their doctors not to share that information, Church says.
Jehannine Austin, president of the National Society of Genetic Counselors, says the decision to screen should be personal. “It’s not necessarily right for everyone.”
A lot of the patients and families she works with want answers to “why” they have particular problems, says Austin, also an associate professor of psychiatry and medical genetics at the University of British Columbia in Canada.
But most genes are not deterministic. They may increase someone’s chances of disease, but they also interact with the person’s environment. Someone with a genetic risk who lives a healthy lifestyle and doesn’t have any additional risks might well avoid what looks like genetic destiny in someone else with a less-healthy lifestyle or who suffers from bad luck.
“Any genomic test results are only going to be able to provide a partial answer for ‘why did this happen to me?’ ” she says.
Austin says she hasn’t yet had her own genome sequenced. Even though she knows genetics aren’t destiny, she’s concerned about how she’d react to any bad news she might hear.
“I know myself well enough to know that if I did have genetic testing that revealed an increased risk, this would exacerbate my anxiety and decrease my quality of life,” she says. “That’s a risk I’m not prepared to take.”