Scientists at deCODE genetics 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 at www.nature.com/ng, 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 outlicensing for therapeutic development,” said Kari Stefansson, CEO of deCODE.

deCODE is a global leader in analysing and understanding the human genome.