Scientists at deCODE genetics today report the discovery of seven novel and common single-letter variations in the sequence of the human genome (SNPs) that are involved in modulating the electrical impulses that govern the working of the heart. Two of these SNPs, which correlate with electrocardiogram (ECG or EKG) measurements that are used in the clinical evaluation of heart health and activity, were then shown to confer increased risk of atrial fibrillation (AF), one of the most common causes of irregular heartbeat and a leading cause of stroke. The paper, “Several common variants modulate heart rate, PR interval and QRS duration,” is published online in Nature Genetics and will appear in an upcoming print addition of the journal.

The deCODE team began by correlating ECG measurements with genome-wide SNP data from more than 40,000 Icelandic participants in its gene discovery program. This search identified one novel SNP influencing heart rate and four each linked to PR interval and QRS duration, measurements of how quickly the electrical impulses that cause the heart muscles to pump achieve their purpose. Intriguingly, SNPs on chromosome 3 linked to both longer PR interval and QRS duration are in the gene encoding SCN10A, a sodium channel that has never before been linked to heart activity. Individuals with the same variants were also more likely to have been fittted with a pacemaker. A follow-on analysis of all of the novel SNPs in Icelandic and Norwegian heart patients and controls demonstrated the association of two of the SNPs linked to PR interval to risk of AF, and another SNP to increased risk of advanced atrioventricular block. Two other papers published today in the same journal provide further validation of some of the deCODE findings.

“Over the past two years, we have discovered major genetic risk factors for heart disease and stroke and introduced tests for these risk factors into clinical practice. We are building the power of these tests through our ongoing discovery work, and today’s findings demonstrate again the fruitfulness of using intermediate risk factors and clinical measurements as entry points for finding risk factors for disease. Our population resources enable us to do so efficiently and with exciting results. These latest findings will be incorporated into our deCODE AF test and deCODEme scans,  and certain of these discoveries may also provide opportunities for out-licensing for therapeutic development,” said Kari Stefansson, CEO of deCODE.

deCODE Discovers Second Common Genetic Risk Factor for Atrial Fibrillation and Stroke. Will be integrated into deCODE AF™ DNA-based risk assessment test, and into the deCODEme™ and deCODEme Cardio™ scans.

Scientists at deCODE genetics and colleagues from Europe and the United States today report the discovery of a common single-letter variant in the sequence of the human genome (SNP) conferring increased risk of atrial fibrillation (AF) and stroke. The findings will be integrated directly into the deCODE AF™ reference laboratory test for gauging individual risk of AF and stroke and helping to identify stroke patients who may benefit from enhanced monitoring for AF. The study is published online today in Nature Genetics.

The new SNP is in the ZFHX3 gene on chromosome 16q22, and the more than one third of people of European descent who carry one copy are at approximately 20% greater risk of AF and cardioembolic stroke than are individuals who carry none. AF is the most common type of cardiac arrhythmia, and is a major risk factor for stroke. Because AF is often intermittent and difficult to detect, gauging genetic susceptibility can help doctors to decide which of their stroke patients might benefit from longer-term monitoring for AF following a stroke. Those with stroke due to AF may be given different therapy than they would otherwise. This is the purpose of deCODE AF™, at the heart of which is the major AF and stroke variant discovered by deCODE on 4q25. Indeed today’s findings are the result of deCODE’s program to build on this work and to find new risk variants. After expanding their genome-wide association study in Iceland, the deCODE team took the top SNPs outside the 4q25 region and typed them in case-control cohorts from Iceland, Norway and the United States. This confirmed the ZFHX3 SNP as a risk variant for AF. Analysis in stroke cohorts from Iceland, Germany, Sweden and the UK demonstrated that this SNP was associated with increased risk of stroke, particularly cardioembolic stroke.

“This is an important discovery and all the more gratifying because we can integrate it straight into a test that is already helping to improve patient care in the clinic.
As with our 4q25 variant, this latest discovery has been replicated in numerous populations by us and others, and the connection to cardioembolic stroke is yet further evidence that we are putting our finger on an important pathway involved in AF and stroke risk. The ability to routinely test for these risk factors means that we can understand whom we should screen intensively for AF and then prescribe the drugs most suited to the cause of a particular patient’s disease. This is the sort of personalized medicine that genetics is enabling – individualized care that may mean not only better outcomes but significant potential savings to the healthcare system. Discoveries like this are the foundation upon which this transformation is being made,” said Kari Stefansson, CEO of deCODE.

deCODE and the authors wish to thank the participants who took part in this study and made it possible. Financial support for this study was provided by US National Institutes of Health grants HL075266 and U01 HL65962 and American Heart Association grant 0940116N; by the German Federal Ministry of Education and Research (01GI9909/3), by the German Migraine & Headache Society (DMKG), and by unrestricted grants of equal share from Astra Zeneca, Berlin Chemie, Boots Healthcare, Glaxo-Smith-Kline, McNeil Pharma, MSD Sharp & Dohme and Pfizer to the University of Muenster.

Amy Doneen, Director of the Heart Attack & Stroke Prevention Center, Spokane, WA.

Amy Doneen at the Heart Attack and Stroke Prevention Clinic in Spokane, Washington, talks about an “exciting new time” for preventive health care. Amy, a nurse practitioner, has been using nutrigenomics (the response of genes to nutrition) as part of the program for more than a decade and with outstanding results. “The goal,” says Amy “is to find out what path a patient is on to developing certain diseases and kick them off that path.” Scanning for risk factor for common conditions (such as diabetes, heart attack, several types of cancer etc.) She emphasizes the importance of gauging lifetime risk as against clinical tests that usually concentrate on immediate high risk. According to Amy, some people walk away from the second kind with a negative result and think things are always going to be fine. Genetic testing is just arriving to the market place, but Americans currently spending nearly $50 billion on stroke care alone, the time is ripe to back all advances in preventive medicine.

To read more and watch parts of the interview with Amy Doneen visit the deCODEme Customer Stories.

Lauralee Nygaard, a periodontist from Spokane, WA, says the deCODE tests are easy to take and highly cost effective but that we have to pay close attention to the results and be prepared to make some serious lifestyle changes.

Lauralee Nygaard is a dentist from Spokane, Washington. She is in her early forties and has two young children. Three years ago Lauralee had a stroke while she was performing surgery on a patient. It confirmed her suspicions about a predisposition to heart disease that she had nurtured since she was 18.

“When I was 18, I went to the doctor and said, ‘I know I’m at risk for a heart attack, my dad has hypercholesterolemia.’ The doctor laughed at me. He said, ‘you’re a skinny girl, you’re never going to have heart disease.”

A stroke at forty confirmed her worst fears: “It corroborated the fact that I knew I was at risk. I had pushed my family physician for years to be aggressively preventative with making sure I didn’t have heart disease. He always told me there was nothing they could do.”

As a dentist who had stressed the importance of preventative care for years, Lauralee was ready to practice what she had preached

Finding the right program

Lauralee had heard about the Heart Attack & Stroke Prevention Clinic in Spokane, Washington from some of her patients who had been through the program there and spoken very highly of it. She was impressed from the very start:

“For me it was one of the most unique health care experiences. My first appointment was three hours long—I had never spent three hours in a physician’s office! They spent a lot of time looking at my family history, asking questions about my uncles and my aunts and other people in the family, and going over my symptoms and educating me about heart disease and we did some follow-up tests.”

After taking the deCODE test she discovered, alarmingly, that her risk for heart attack and stroke was considerably higher than the average.

The program at Heart Attack & Stroke Prevention Clinic was quite unlike anything she had experienced before: “I had seen my physician annually for my entire life. I’d always had perfect blood pressure, always had perfect blood work. So, for them to say that ‘well, you had a stroke we’re not sure why’—I just thought, what did they miss? I mean there’s got to be something else. That was just really disturbing. Was I at risk because someone missed something?”

Lauralee expressed her disappointment and frustration with what she calls the ‘five-minute, drive-by doctor’s appointment’. She explains: “even if a physician wants to give you options, he’s not allowed to if he’s on certain insurance plans,” and that most physicians are restricted under the present system.

However, she insists that paying out of her own pocket at the Heart Attack & Stroke Prevention Clinic allowed nurse practitioner Amy Doneen “to have time with patients and be more preventative in terms of her approach to disease.” Lauralee adds that the costs of preventative treatment, as opposed to those incurred after an incident such as stroke or heart attack, are minimal.

The benefits of genetic testing
“To me, the benefit of doing the genetic test is that I can reduce my risk of having another stroke and permanent damage. It’s a short life, you know . . .”

deCODE offers genetic testing for a range of inheritable diseases. This, Lauralee believes, is part of a more efficient and more cost effective method of treatment.

“The motivation for me to follow through with the genetic test was the fact that my mother’s health had been failing rapidly and she had had four strokes in the last six months. She had just been diagnosed with diabetes and was not doing well. I had never really figured out why I had a stroke. Then Amy Doneen at Heart Attack Prevention Clinic suggested that atrial fibrillation (irregular heart rhythm) might have played a role. She explained to me that 30% of cryptogenic stroke diagnosis comes from atrial fibrillation and that this condition was ‘preventable’ with the right medication.”

To her surprise, Lauralee tested negative for the diabetes gene she believed she had inherited from her mother. But the test results affirmed that her stroke has not been a random catastrophe and she did indeed have a genetic disposition for atrial fibrillation. The next step was to take blood thinners that would reduce the risk of clotting after irregular heart rhythm and subsequently reduce the risk of having a stroke.

“The genetic test gave me information (that confirmed with my past stroke) that I am at risk for future strokes. Now, instead of saying, ‘Oh well, I had a stroke. I got lucky—no big deal,’ I can actually make some choices with my health care and avoid another stroke altogether.” Lauralee’s mother had suffered a series of strokes over a short period of time and she did not want to follow along the same path.

“My kids are little—I have kids that are 8 and 10 years old and I would like to be around to see them become productive adults. I think if I could gain some information, I’d be more proactive in my health—I think there’s a lot of benefit in that.”

By the same token, she believes that her children have “so many more preventative options” and could be tested at a much younger age and therefore hopefully avoid an incident altogether. She did not want them to have to wait till 40 or 50 and/or the occurrence of a massive event. Finding out early that they could be at risk would mean earlier intervention.

Modifying behavior for optimum health
Lauralee explains a healthy future is a matter of first getting as much information as possible and then modifying one’s behavior:

“I think things are changing. We’re learning more about how being aware impacts people. I think the more you can learn about your risks, the more you can modify your behavior and the more you can hopefully prevent something that’s going to harm or shorten your life.”

Of course, knowledge can be intimidating, but only if one is not willing to make lifestyle changes. Lauralee claims that the people who are frightened of what genetic testing can offer are mainly those who don’t want to change how they’re living. She admits she had to make some serious changes in her own life, changes that she frowned on several years before her stroke.

Cost effective
Lauralee says some people are naturally concerned about costs and the fact that their insurance might not pay for genetic testing. However, if you find out you are at risk before you damage anything, you can save a great deal. She believes that preventative medicine and genetic testing are highly cost effective!

“We know that a simple swab from the inside of your mouth can gauge your disease risk—that’s a very cost effective test to figure out what your disease predispositions are. Certainly, being more aggressive in prevention is going to lower health care costs over time. For example, it would have cost a lot less for me to know that I was at risk than to have 3 MRIs—in terms of health care expense. On the national scale, heart disease, diabetes, and stroke are some of the greatest issues facing health care in this country at the moment and they’re eating up a good chunk of our health care budget.

Better decisions, better health
After describing the test as “ridiculously easy,” Lauralee admitted that some fears were “a generational issue.” Younger people are much more comfortable with technology and knowledge and do not regard knowing what their genetic makeup is as threatening. People will soon learn that knowledge is power and that it allows us to take better care of our health and make better decisions. She admits, though, that any fears she might have had are allayed by a background in biology. She certainly did not shy away from being proactive: “I mean, I think that you can never ever regret what you invest in taking care of yourself. One body, one life, one chance.”

Does that mean she was glad to have an early warning?

“Yes, totally—it was a blessing. I was very fortunate I got a warning and could shape a path for myself. Not everyone does. 70% of all first heart attacks or strokes result in death for patients.”

She ends by telling us how the pharmacist reacted to her new medication regime:
“My pharmacist, who looks sixteen, said: ‘Can I ask you a personal question? Why are you taking all this medicine?’ (blood thinners, blood pressure and cholesterol medications) I said ‘you mean the medicine of an 80-year-old?—that’s because I want to live to be 80!’”