Sick sinus syndrome (SSS) – a disorder that slows the heart rate and increases the risk for atrial fibrillation – is the most common reason for implanting a cardiac pacemaker.
Dawood Darbar, Dan Roden and colleagues at deCODE genetics in Iceland have identified a novel susceptibility gene (MYH6) that increases the risk for developing SSS. MYH6 encodes a myosin protein that is part of the heart’s contractile machinery. The investigators identified a rare variant in the gene that confers a 50 percent lifetime risk of SSS (individuals who do not carry the variant have a 6 percent risk).
The researchers also showed that other common variants in MYH6 affect heart rate, demonstrating the interplay between common and rare genetic variants in complex diseases.
The findings in Nature Genetics establish the importance of cardiac myosin in the development of heart rhythm disorders. The Vanderbilt AF Registry, an ongoing clinical and DNA registry of patients with atrial fibrillation, contributed patient samples to the study.
Funding for the study was provided by the National Heart, Lung and Blood Institute.
