MORE than 50,000 Scots are carrying a faulty gene that puts them at high risk of developing coronary heart disease or sudden death - but most have no idea that they are at risk.

The figure is 18,000 higher than previous estimates due to better understanding of the prevalence of inherited heart conditions, but the British Heart Foundation warns that the true incidence could be much higher due to under-diagnosis and undiscovered faulty genes.

It also stresses that the majority of people carrying the genes will not have been diagnosed and are therefore unaware that they are at a heightened risk of suffering a heart attack or cardiac arrest regardless of their lifestyle and fitness.

Read more: Health service risks continued failure without major change, warns watchdog

Each week in the UK, around 12 seemingly healthy people aged 35 or under are victims of sudden cardiac death with no explanation, largely due to these hidden heart conditions.

Victims have included Scottish footballer Phil O'Donnell, who collapsed on the pitch and later died aged 35 while playing for Motherwell against Dundee at Fir Park in December 2007. He had suffered a cardiac arrest which pathologists later blamed on hypertrophic cardiomyopathy, an inherited disorder which causes abnormal thickening of the heart muscle.

Children whose parents carry the faulty genes have a 50 per cent chance of inheriting it but for many families, the first sign there’s a problem is when someone has a sudden cardiac arrest with no obvious cause or explanation.

Read more: Health service risks continued failure without major change, warns watchdog

The charity, which has funded research to pinpoint many of the faulty genes that cause inherited heart conditions, is launching a new campaign to raise awareness of the genetic testing services available and to call for further research to improve detection.

Ross Peters, 23, from Dundee is among those backing the campaign. He was diagnosed in September 2015 with dilated cardiomyopathy (DCM), an inheritable disease of the heart muscle which causes it to become stretched and thin and stops the heart being able to pump blood around the body efficiently.

It was picked up after Mr Peters fell ill suddenly while on holiday and his heart was found to be twice the size it should be.

His younger brothers, 20-year-old Ryan and Aaron, 19, have been tested for the gene and are still awaiting the test results, while their father Norrie has been identified as a carrier. Although he is not seriously ill, he does have a fast resting heart rate.

Mr Peters, who works in the family’s electrician firm, said: “Obviously I’m devastated that my brothers might have something wrong with them, because I’m quite protective of them, but at least we know how to tackle it. If they started displaying symptoms they’d get medical attention straight away and, as a family, we’d know how to deal with it."

Read more: Health service risks continued failure without major change, warns watchdog

Professor Sir Nilesh Samani, Medical Director at the British Heart Foundation, said: “The reality is that there are thousands of people across Scotland who are unaware that they could be at risk of sudden death.

“If undetected and untreated, inherited heart conditions can be deadly and they continue to devastate families, often by taking away loved ones without warning."