Genes that may cause sudden cardiac death

Washington: Most sudden cardiac deaths are caused by abnormal heart rhythms called arrhythmias and researchers have uncovered new information about genes that may increase the risk of serious cardiac arrhythmias.

The researchers identified several new gene regions associated with variations in the QT interval - a stage in the heart's electrical cycle that, if prolonged, increases the risk of drug-induced arrhythmias and sudden cardiac death.

A surprising finding of that paper was the extent to which genes involved in calcium signalling influences the QT interval, the time from electrical activation of heart cells, which stimulates contraction, to the end of electrical relaxation.

"We have known that calcium signalling is critically important in regulating the contraction of muscle cells that generate heartbeats," said Christopher Newton-Cheh from Massachusetts General Hospital (MGH) in the US.

"But finding that calcium is also involved in resetting the heart after each beat was a total surprise and represents a new avenue to pursue the causes of arrhythmias," he added.

The discovery has been described as a quantum leap in our ability to study one of the major causes of death in people with heart failure - which is well known to involve calcium abnormalities - and an important cause of fatal arrhythmias that occur as a side effect of several medications.

"Like people, genes like to work in groups, and we used the newest technologies in genomics and proteomics to derive the working group of genes involved in processes that coordinate the beating of the heart and, when malfunctioning, can cause arrhythmias or sudden cardiac death," Kasper Lage from MGH noted.

The study describes a meta-analysis of genome-wide association studies (GWAS) involving more than 100,000 individuals that identified 35 common gene variant locations - 22 for the first time - associated with alterations in the QT interval.

The study appeared online in the journals Nature Genetics and Nature Methods.

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