Faulty link to gene linked to sudden death of 'much-loved' man (23)
Nearly a fifth of people carrying a deadly inherited heart condition are only diagnosed after a sudden death in the family, a charity has said.
The figures were released as part of a campaign to raise awareness and highlight the need for more research.
The British Heart Foundation Northern Ireland (BHF NI) found that of those living with an inherited heart condition, 18% are diagnosed after the sudden death of a family member.
They include relatives of Joe Burns from North Belfast, who died in July 2014 after collapsing at his parents' home.
The 23-year-old, who was a barman at The Chester Bar, was a fit and healthy boxer who trained regularly at the gym.
The day after his death his girlfriend Sinead discovered she was pregnant with their daughter Bella.
Joe's family spent months not knowing how he died.
They were referred to the inherited heart conditions clinic in Belfast for genetic testing.
They have since learned Joe's mum Una and sister Jeanette both carry the faulty gene for Long QT (LQTS), an inherited condition that can cause heart rhythm disturbances. Left undiagnosed, it can cause sudden death where someone has an unexpected cardiac arrest.
Jeanette said: "When Joe died our family was absolutely devastated. He was the only boy in our family and everyone just loved him, he was so well known in north Belfast and after his death so many people contacted us to say what a gentleman he was. He made such a big impact on so many people.
"We didn't know what had caused his death and it was hard dealing with that because we didn't have any answers. We were referred to the inherited cardiac conditions service in Belfast and after tests we discovered that my mum Una and I carry the faulty gene for Long QT so it is very likely that is what Joe died from."
Long QT syndrome causes an electrical disturbance to the heart and puts those affected at risk of having a dangerous heart rhythm. Some people experience no symptoms at all but others may faint or collapse. In some cases, LQTS can cause sudden death.
"It's very hard to hear that you carry the gene for a potentially deadly heart condition but thanks to the testing we now know we have this gene and can be monitored," added Jeanette.
The figures also show one in six people (16%) with a deadly inherited heart condition are only diagnosed after having a cardiac arrest.
BHF NI estimates that around 17,500 people in the Northern Ireland have a faulty gene which puts them at an unusually high risk of developing heart disease or dying suddenly at a young age.
Each child of someone with an inherited heart condition has a 50% chance of inheriting the same faulty gene. But the majority of people remain undiagnosed.
In Northern Ireland it is estimated that at least one person aged under 35 dies every month from an undiagnosed heart condition.
Jayne Murray from BHF NI said: "All too often, people aren't familiar with their family history, or they aren't aware that a sudden death might be linked to an underlying heart condition.
"We need to improve awareness of these conditions, and ensure that people have equal access to cascade genetic testing across the UK."