Scientists combing the human genome have discovered ten common genetic mutations that boost the risk of sudden cardiac arrest by subtly disrupting the heart beat, two new studies report.
The findings shed light on the cause of the irregular rhythms that
often underlie severe heart problems, and could point to new
treatments, said a study, published in Nature Genetics.
Heart disease is the number one killer worldwide, claiming upward of
17 million lives every year, according to the World Health
Smoking, obesity and high cholesterol are common risk factors, but
genes can be a critical factor too.
In the absence of symptoms, identifying genetic variants that affect
the timing of heart contractions - known as the "QT interval" - could
become a critical means of predicting the likelihood of sudden cardiac
How the research was done
An international team of more than 40 scientists, led by Arne
Pfeufer of Munich University, analysed the genomes of nearly 16 000
individuals whose QT intervals had been measured by electrocardiogram.
They screened some 2.5 million sites on each genome, trying to match
subtle alterations in gene sequence with aberrant patterns of heart
The study turned up ten bits of wayward genetic code. One, a gene
known as Nos1ap, had already been identified as contributing to heart
trouble, and several others had been placed on a list of suspects.
"But almost half were surprising new genes that no one would have
guessed as being involved in cardiac biology," said Dan Arking, a
professor at John Hopkins University in Baltimore, and a co-author of
"So it really does open up a new world of investigation because
these are genes that would have never come up if we had only focused on
a list of known candidates."
In separate research, scientists led by Christopher Newton-Cheh at
Massachusetts General Hospital found similar results from more than
13 000 individuals.
"We were very reassured to see such strong replication in two
independent studies," he said in a press statement.
A single genetic variation in an individual does not necessarily
mean a higher risk of an irregular heart beat, much less increased risk
of sudden cardiac death, the researchers pointed out.
But when all the data is taken together, the results become
statistically significant. – (Sapa, March 2009)