DeCode C.E.O. Kari Stefansson is on the telephone from Iceland insisting that I immediately go on statins—cholesterol-lowering drugs that help prevent heart disease. A physician as well as an entrepreneur, he has just told me I am at a high risk for a myocardial infarction—a heart attack—based on a gene test run by his company.
"You have a very bad gene marker," he says, "you need to take this seriously!"
I had just begun my own personal journey to delve into millions of DNA markers inside me to check for diseases, and already things were looking dire. Or were they? In the weeks after Stefansson's call, I would receive results from three new websites that tested my DNA and offered assessments of my personal genetic risk factors for not only heart attack, but also a raft of diseases ranging from diabetes to multiple sclerosis.
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The findings suggest that this information is based on an exciting but still uncertain science that can produce contradictory results about something I take pretty seriously: my heart.
Stefansson had called me about a genetic marker identified by scientists as rs10757278. Last year, researchers at his company and elsewhere linked a certain version of genetic coding in this marker with an elevated risk of heart disease. This "variation" was discovered by comparing the genes of people in North America and Europe who have had a heart attack to those who haven't.
In the language of genetics, the high-risk result for this marker is a GG—the "G" coming from the familiar genetic symbols for nucleotides (G, T, C, and A) that are arranged in pairs along lengthy strings of DNA. These "base pairs" line up like computer code to direct the growth and functions of cells. Differences in these codes—in the letters—are what accounts for variation among people: everything from the color of one's eyes to the likelihood of developing a certain disease.
About 20 percent of Caucasians carry the GG, which confers about a 1.64 times the average risk factor for a heart attack—a 64 percent greater risk than average. This is a moderate risk compared with, say, someone with high cholesterol, who has at least two times the normal risk.