Family of Four Has Its Genome Sequenced

By on September 16, 2011

FRIDAY, Sept. 16After John West, an executive in the genetics industry, suffered two pulmonary embolisms in 2003 because of a genetic mutation he carries, he decided to have his two children tested to see if they had inherited the same vulnerability for dangerous blood clots.

That testing determined that his daughter, Anne, but not her brother, also has what is known as a Factor V mutation. For Anne, that meant that she would take steps to limit her risk of clots, such as avoiding birth control pills. As she ages, she may eventually need to take a prescription anti-clotting medication.

“It doesn’t mean I’m for sure going to get an embolism. But I’ve just become more aware of things to prevent it and make it less likely by staying hydrated, moving around on long plane rides and not taking birth control [pills],” she said.

Now, the California family has had their entire genome sequenced, the results of which allowed physicians to get a more accurate look at the family’s risk for everything from blood clots to obesity.

Though whole genome scanning is still rare today, researchers say the cost of sequencing is rapidly falling. Within a few years, they predict it will become increasingly common for people to walk into their doctor’s offices carrying their genome analysis, which physicians could then use to make recommendations about medications, treatments or lifestyle changes.

While much of genetic testing has so far been limited to searching for specific genes associated with diseases such as breast cancer or Grave’s disease, whole genome scanning can give clues about a wide range of conditions from various types of cancers to heart disease to diabetes.

In the case of the West family, all four members of the family also have a heightened risk for psoriasis and melanoma; everyone but the son has a slightly higher risk of esophagitis, or an inflammation of the esophagus.

And while mom and dad have genes that put them at higher risk of becoming obese, neither of their children do.

“You have your standard lab testing, your exam and your information about family history. What we are showing here is that the addition of the genome sequence can refine that risk estimate,” said study author Frederick Dewey, a fellow in the division of cardiovascular medicine at Stanford University. “With obesity, for example, dad and mom are at increased risk, but the boy and the girl are at less risk. That’s information we wouldn’t have known if we asked for a family history of obesity.”

The findings are published in the Sept. 15 issue of PLoS Genetics.

“This work pushes the boundaries of our understanding of personal genomes by adding the strength of family genetics to the technology of genomics,” Rochelle Long, director of the U.S. National Institutes of Health Pharmacogenomics Research Network, said in a Stanford University statement. “The advance promises a new era of personalized medicine in which people will be able to make informed decisions about medical treatment based on their individual genetic risks.”

Finding out she had the mutation led Anne, then in high school, to start delving into her family’s genetic make-up as a science project.

Until recently, whole gene sequencing has been too costly. The Human Genome Project produced the first whole human genome in 2001 at a cost of about $3 billion. By 2010, sequencing an entire genome cost around $50,000, while today the cost is closer to $4,000, said senior study author Dr. Euan Ashley, director of the Stanford Center for Inherited Cardiovascular Disease in Palo Alto, Calif.

“The pace of change of the technology is radically altering the landscape,” Ashley said.

The family first approached the researchers at Stanford, who did a fuller analysis, the results of which are published in the journal. Anne and her father, John, are both co-authors on the paper.

What they found in the family’s genetic code was compared with 17,000 published papers identifying genetic variants that are associated with more than 30 diseases, from cancer to autoimmune disorders to stroke and heart disease.

While some members of the family are at slightly increased risk of certain conditions, they’re also at low risk of other diseases, such as type 1 diabetes and multiple sclerosis.

“It was a relief that I don’t carry a lot of added genetic risks for most things,” said Anne West, a freshman at Wellesley College in Massachusetts who wants to study biology. “If I had been at risk for something severe like Alzheimer’s, I’m not the sort of person that would let that get me down. I would donate my money and possibly my time toward researching and preventing Alzheimer’s later on, and doing what I could to prevent it.”

And, she noted, having a higher risk for a disease doesn’t mean you are destined to get it, just that you have some genes that raise your risk higher than others.

“If you know what’s in your genome and you know what diseases you’re at risk for, if you have a problem, you will be able to identify it much more easily,” she explained.

Still, there are limitations, the researchers acknowledged, including that much of what is revealed in the genetic code is far from being fully understood.

And there’s also the question of how much people want to know about what medical miseries may lie ahead, and to what extent people will change their behavior to prevent what they can.

“There are many things we’re going to find when we do this work that have no specific prevention or cure,” Ashley said. “That is one of the ethical questions the field is going to have to wrestle with.”

More information

The U.S. National Human Genome Research Institute has more on genetic testing.

Source: HealthDay

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