Breakthrough genetic test will pinpoint mutations harmful to the heart

Around 2000 young people under 50 suffer a sudden cardiac arrest each year, but now a breakthrough test can detect if healthy young people have a deadly gene hidden in their DNA.

When Victoria Macarthur-Stanham began suffering fainting episodes, she put it down to the exhaustion of being a new mum – until she had a near-fatal cardiac arrest at home.

The Coledale mother owes her miraculous survival to husband Tim, who performed CPR for 16 minutes until paramedics arrived.

But it also saved both her baby girl Indigo and her mother Edwina because it revealed the family carries a genetic mutation that can cause sudden cardiac arrest and now they can be protected too.

A new test developed by the Victor Chang Cardiac Research Institute (VCCRI) has made it easier for families to discover if they are carrying genetic mutations that cause sudden cardiac arrest – an inherited heart arrhythmia condition called long QT syndrome type 2.

The VCCRI team has developed a fast and accurate test using robots that can screen hundreds of gene mutations to pinpoint the exact mutations that are harmful to the heart.

Victoria Macarthur-Stanham with her mother Edwina and baby girl Indigo. All three carry a gene for long QT syndrome which can cause sudden heart attack

Professor Jamie Vandenberg, who led the research that was published in the American Journal of Human Genetics, said it was primarily young people who die from these inherited heart disorders.

Inherited arrhythmia disorders are found in more than half of all initially unexplained cases of sudden cardiac death in young people.

“If you look at the population under 50 in Australia, about 2000 in that age group will have a sudden cardiac arrest of death each year,” he said.

“When it occurs in someone young, there is almost always going have a genetic contribution for someone under 50.

“The classic is the teenage kid on the sporting field you think is perfectly healthy and just collapses, that is often the first indication there is something wrong. If you identify an index case you can screen through the family and see who else is at risk.”

Victoria Macarthur-Stanham’s husband kept her alive by doing CPR waiting for the ambulance to arrive.

The majority of genetic disorders that lead to an increased risk of sudden cardiac arrest are caused by these mutations.

“When you detect the first person, we know other members in their family will also be at risk, so we need to identify those people as quickly and accurately as possible, so we can prevent sudden cardiac arrest,” he said.

Fellow author Dr Chai-Ann Ng said identifying these dangerous mutations will help prevent people dying from sudden cardiac arrest and ensure more people are treated for this life-threatening disorder.

“If you can isolate the mutation and identify those at risk, there are lifestyle changes people can make, as well as taking beta-blockers or even using a defibrillator,” Dr Ng said.

The vast majority of young people like Ms Macarthur-Stanham have no idea they have long QT syndrome.

“It was like any ordinary day … went to work, came home, had dinner, played with my little girl and I was just tying off emails at 9pm and my husband heard a thud and I was unconscious on the floor,” she said.

The report’s author Dr Chai-Ann Ng said identifying these dangerous mutations carried by Victoria Macarthur-Stanham and her baby will help prevent people dying from sudden cardiac arrest

“He called triple-0 and fortunately he is a trained lifeguard, so he knew how to perform CPR, which saved my life.”

After Ms Macarthur-Stanham survived her cardiac arrest, her family was screened and both her mother Edwina and her youngest girl Indigo were found to carry the gene for Long QT.

Ms Macarthur-Stanham and her mother Edwina, 61, have now been fitted with a combined pacemaker and defibrillator to mitigate their risk of a sudden cardiac arrest. Four-month-old Indigo will be treated with beta-blockers.

“Fortunately for the particular variant Victoria and her mum have, it is not really severe when they are young,” Prof Vandenberg said.

“In this syndrome, the classic high risk period is after pregnancy. In that sense Victoria was a classic case after the birth of her second child. With children we treat them with beta blockers and monitor them closely.”

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Originally published as Breakthrough genetic test will pinpoint mutations harmful to the heart