Ellen Phiddian
Cosmos science journalist
An international team of researchers has developed a way to predict risk for people with the heart condition Long QT syndrome.
Long QT syndrome is a heart rhythm disorder, usually caused by genetic mutations. It creates electrical fluctuations which stop the heart from beating, leading to fainting, seizures, and in some cases, sudden death.
The condition affects about 1 in 2,000 Australians, but its severity can vary.
The tool, which is described today in a paper in Circulation, uses genetic information to establish heart disease severity.
“Genetic testing for inherited heart diseases has been transformative, but there have been limitations in what it can tell you,” says lead author Professor Jamie Vandenburg, deputy director of the Victor Chang Cardiac Research Institute in Sydney.
“It might reveal you have the disease, but there has been no way of using this genetic information to determine how high your risk is for suffering a sudden cardiac arrest.”
Vandenburg and colleagues examined 533 genetic mutations linked to Long QT syndrome, taken from the genomes of 1,458 patients.
Each of these mutated genes are related to ion channels – proteins in the heart which transport electrically charged ions.
The team used a high-speed electrical test to see how each of these genetic mutations affected the performance of the ion channels they were linked to.
Using these findings and patient records, the team was able to figure out which genetic mutations are the most dangerous.
Some mutations made ion channels perform 90% worse, leading to a 13.3-times greater risk of arrythmia and sudden death.
Other mutations made ion channels perform 75% worse, which was linked to an 8.6 times greater risk of arrythmia and sudden death.
“We have shown that not every diagnosis of Long QT is equal, and the risk of having a sudden cardiac arrest can vary dramatically depending on the exact genetic mutation,” says co-author Dr Chai-Ann Ng, also from the Victor Chang Cardiac Research Institute.
“Our findings will make a huge difference in how these high-risk patients are cared for in the future. We are also actively working on adapting this test to patients affected by other heart arrhythmias and neurological conditions.”
