Ten genes identified in connection with sudden car...( ANN ARBOR Mich.---You're sitting at ...)

ANN ARBOR, Mich.---You're sitting at your desk and suddenly your heart is beating in overdrive or worse, lurching along like a car on fumes. It is a shocking, uncomfortable and frightening sensation.

Irregular heart rhythms are a common cause of sudden cardiac death or SCD, a condition that accounts for 450,000 deaths annually in the United States. Scientists are now closer to understanding what causes SCD and who it may strike, said Gonalo Abecasis, associate professor of biostatistics at the University of Michigan School of Public Health.

Abecasis co-led on an international study aiming to identify genetic defects associated with sudden cardiac death. Aravinda Chakravarti of Johns Hopkins and Arne Pfeufer of the Institute for Human Genetics in Germany also co-led the study. Serena Sanna, formerly at the U-M School of Public Health and now a researcher at the National Research Center in Cagliari, Italy, was joint first author.

The team identified 10 genes associated with changes in the so-called QT interval duration. The QT interval duration measures the length of time the heart takes to contract. A QT interval that's too long or too short can cause serious problems, including arrhythmias and sudden cardiac death. The QT interval can be seen on an electrocardiogram monitor; it's a certain portion of the line that waves or spikes up and down when the heart contracts.

The genes are interesting for several other reasons, Abecasis said. Changes in the QT interval are one of the common side effects that lead pharmaceutical companies to cancel new drugs that are under development, Abecasis said. This discovery could help identify individuals most at risk of that complication and, eventually, help the industry develop drugs that avoid that complication altogether.

The genes also confirm existing medical theory. A number of the 10 genes help regulate human potassium channels in the heart muscle, reinforcing the idea that
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