The cost of mapping a person’s full genetic profile has been dropping quickly. Now, doctors are struggling with a new question: how to use the information to improve people’s health.
Genetic profiling, known as genome sequencing, already is helping researchers diagnose rare or mysterious illnesses. Other specialists use the process to tailor drug therapies for advanced cancer patients. The latest research focuses on how to use genome sequencing in basically healthy people, especially those who may have a family history of disease but no symptoms.
The price to get a full genetic map currently starts at about $3,000, and many experts predict this could quickly fall to $1,000, roughly equivalent to the cost of an MRI. Insurance is expected eventually to help cover the cost of doctor-ordered tests.
At such prices, some experts and health-care companies are predicting that genome sequencing will one day become common practice in doctors’ offices and hospitals as a means of guiding prevention and treatment of illnesses.
“Whole genome sequencing will not stay confined to extremely rare cases of obscure diseases,” says Robert C. Green, a geneticist at Boston’s Brigham and Women’s Hospital and Harvard Medical School. “If there is a way to use sequencing in day-to-day medicine, we need to find out.”
Some tests looking for individual genes already are common. For instance, women found to have the mutations known as BRCA1 and BRCA2 might be at increased risk for breast and ovarian cancers. But these tests can merely confirm the presence of particular genetic mutations. By contrast, whole genome sequencing can provide information on conditions that might not have been previously suspected.
One condition being studied to see if whole genome sequencing can help is hypertrophic cardiomyopathy, a thickening of the heart muscle that can cause sudden cardiac death. A genetic mutation for the disorder is fairly common—affecting about 1 in 500 people—although not everyone with the mutation will suffer heart failure. Prevention strategies, including surveillance and medication, can be used to lower risk.
Dr. Green is heading a new clinical trial involving 200 people, half of whom have hypertrophic cardiomyopathy and a family history of the disorder. The other trial participants are middle-aged and relatively healthy. Dr. Green says the aim of the trial is to see what patients and their primary-care doctors do with the genetic information, including changing lifestyle, prescribing drugs and ordering additional tests.
Some specialists say full genetic mapping often has limited use. For diseases like diabetes and heart disease, which have many causes beyond genes, genome sequencing isn’t able to predict who will get sick. Even proponents say the clinical significance of nearly all of the millions of mutations found in a person’s DNA is still unknown.
“Everyone has genetic variations” many of which will never cause disease, says Michael S. Watson, executive director of the American College of Medical Genetics and Genomics, a professional organization. If the risk of disease is overestimated, it could drive up health costs and cause unnecessary worry, he says. Still, the group issued a policy statement in March that said there are instances where whole genome sequencing can contribute to clinical care, such as in detecting mysterious diseases.
Genome sequencing also presents ethical questions. Some patients may not want to know and may be distressed to find out if they have genes that put them at higher risk for certain diseases. Some genome labs in reporting results will only include information about genes linked to diseases that have known treatments or prevention strategies.