Genetic tests for specific cancers and other diseases have become common today. Now Partners HealthCare System is taking the next step, sequencing entire genomes for patients.
While genetic tests target certain genes to check for specific disorders, whole genome sequencing maps all of the body’s 3.2 billion nucleotides — the building blocks of DNA — that should appear in predictable patterns.
Deviations from the norm can indicate that someone is genetically predisposed to certain health problems or is likely to pass them on to children.
Because it is so much more comprehensive, genome sequencing has the potential to identify health risks that targeted testing might miss. It could enable patients to personalize their treatment plans like never before.
“We can sequence an entire genome in a healthy person or a diseased individual and figure out what’s wrong,” said Heidi L. Rehm, director of the Partners Lab for Molecular Medicine. “Hopefully we can better decide how to treat the disease or predict a disease they were absolutely unaware of and improve their outcome because we catch something even before they develop symptoms.”
Last year, Partners became one of the first health care systems in the nation to offer patients full genome sequencing, a process that costs $9,000 and is not normally covered by insurance. Rehm said her lab performs only a couple of sequences per week, partly because of the sticker shock.
Broad adoption of genome sequencing depends on convincing insurers the process will save money in the long run, she said. Warned of impending heart disease, for instance, a woman might avoid future surgeries and prescriptions by changing her diet and becoming more active.
But another question will also influence whether patients start asking to be sequenced in droves: How much information is too much?
The idea of catching diseases before symptoms even appear is appealing. But some patients may not want to know about looming problems that cannot be prevented or even treated when the symptoms eventually arrive.
Rehm said she understands why someone might choose not to learn of a future disease for which there is no cure. But she contends there are also benefits to that knowledge. Such cases can inspire medical researchers to seek new breakthroughs and motivate patients to become advocates.
“Even if on day one when you’re diagnosed there’s no treatment, there’s a lot you can do with the power of information,” Rehm said.