An Australian study of sudden cardiac death has found a genetic link that will lead to better prevention strategies for family members at high risk.

Australian research into the sudden cardiac deaths of thousands of young Australians and New Zealanders has uncovered a genetic link, which will be used to prevent further deaths for high-risk family members.

A new study led by Sydney cardiologist Professor Chris Semsarian from the University of Sydney, and published in the New England Journal of Medicine, reveals a genetic link to many unexplained cases of sudden cardiac death (SCD).

SCD claims the lives of two to three young Australians every week, that's around 30,000 people each year, and in 40 per cent of cases their deaths are unexplained.

A team of researchers investigated 490 cases of SCD occurring among people aged one to 35 years from 2010 to 2012.

They found a cause of death in 60 per cent of cases (292) by reviewing information from autopsies, coronial and police reports.

To understand the remaining 198 unexplained cases, researchers conducted blood analysis and family screening and found one in four, or 27 per cent, unexplained sudden cardiac deaths had a genetic mutation.

Prof. Semsarian says it's this knowledge that will save lives by providing preventative treatment options for existing family members at risk of sudden cardiac death.

"If you work out the gene fault that caused the young person to die suddenly you can test the relatives of the individuals for that genetic mutation and if the relative has the same gene mutation then they are at risk of dying suddenly as well.

"In that case we would put them on treatment, so either medical therapies like beta-blockers or devices where we implant defibrillators inside the chest wall," he said.

Chris Britton was left with no answers when his sister Michelle died suddenly from a cardiac arrest at age 39 in 2009.

He says genetic testing has helped his family understand what happened to his sister and given them some control back, which is "absolutely huge".

"To not have an understanding is a tragedy in its own right," Mr Britton said