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A genetic variant associated with sudden cardiac death leads to protein overproduction in heart cells, a new study has reported. The variant, unlike many known disease-linked variants, lies in a so called noncoding DNA.

The discovery adds to scientific understanding of the causes of sudden cardiac death and of possible ways to prevent it, according to the press release. 

"Traditionally, geneticists have studied gene variants that cause disease by producing an abnormal protein," said Aravinda Chakravarti, Ph.D., a professor of medicine, pediatrics, molecular biology and genetics, and biostatistics in the McKusick-Nathans Institute of Genetic Medicine at the Johns Hopkins University School of Medicine, in the press release. "We think there will turn out to be many DNA variants that, like this one, cause disease by making too much or too little of a normal protein."

The press release added that Chakravarti's interest in sudden cardiac death emerged a decade ago, when it claimed several of his colleagues within a few months. 

Researchers compared the genetic sequences of tens of thousands of people with their electrocardiogram (ECG) results and identified several regions on the genome with genetic variations associated with lengthened QT interval - a measure of cardiac repolarization - in the ECG.

"The problem is that most of these variants lie outside of genes, in the noncoding DNA that controls how genes are used," Chakravarti said, "so it's hard to tell what genes they're affecting."

"Hundreds of genome-wide association studies have been done to find genetic variants associated with disease, but this is one of just a handful of follow-up studies to look for the mechanism behind such a variant," Chakravarti added in the press release. "I think we've shown there's great value in asking why."

The study is published in the June 5 issue of The American Journal of Human Genetics.