A newly identified gene has been linked to about 55 percent of cases of an inherited heart disorder that can kill young, otherwise healthy people.
It’s the third gene to be found for the inherited form of the illness known as “long QT syndrome,” which affects an estimated 20,000 Americans and is thought to cause 50 to 200 deaths a year.
People with the disorder have an increased risk for episodes in which their heart races at 300 to 400 beats a minute, too fast to pump blood effectively. These episodes lead to fainting and sometimes death. QT is simply a label for a measure of the time it takes for the heart to get set for its next beat.
Finding the third gene will help in diagnosis, said researcher Dr. Mark Keating.
While the inherited condition is rare, knowing the three genes that cause it also suggests a possible strategy for treating a more common problem of abnormal heartbeat, called ventricular tachyarrhythmias, which kills some 300,000 to 400,000 Americans a year, Keating said.
The three genes tell heart cells how to make structures called ion channels that regulate heartbeat. The genes cause trouble when defective. So maybe channel malfunctions that don’t come from gene defects cause other cases of ventricular tachyarrhythmias, Keating said.
Drugs that correct malfunctioning ion channels show promise for reducing the death rate from inherited long QT syndrome, so they might also cut the risk of dangerous abnormal heartbeat after heart attacks, Keating said.