By BBC Health
An estimated 620,000 people in the UK have a faulty gene that puts them at risk of developing coronary heart disease or sudden death, and most are unaware, a charity has warned.
The British Heart Foundation said the figure was 100,000 more than had been thought and could be even higher.
It said there was now a better grasp of the prevalence of inherited conditions.
A child of someone with an inherited heart condition can have a 50% chance of inheriting it themselves.
The charity warned that the overall figure for those with the faulty gene could be much higher because of as yet undiscovered faulty genes and under-diagnoses.
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 undiagnosed heart conditions.
Former England and Nottinghamshire cricketer James Taylor had to retire last year, at the age of 26, after he was diagnosed with the serious heart condition arrhythmogenic right ventricular cardiomyopathy.
He told BBC Radio Four’s Today programme that he had been warming up for the first game of the season in Cambridge when his heart started “going mental in my chest”.
He said: “You could see my shirt moving, that’s how hard my heart was beating inside my chest…
“I went off, I had some oxygen, then I went to hospital some hours later.
“When I walked in to hospital they said it was a miracle I was able to walk in.
“My heart rate was going at 265 beats per minute.”