The British Heart Foundation has estimated that 620,000 people in the UK are carrying a carrying a faulty gene that puts them at high risk sudden death, but warns that the majority are unaware of this.
The charity also noted that the actual figure could be much higher because of underdiagnosis and undiscovered faulty genes, which can raise a person's risk of suffering potentially fatal conditions.
These conditions can affect people of any age and can be inherited but, for many families, the first sign that of a problem is when someone dies suddenly from a cardiac arrest or heart attack with no obvious cause or explanation.
"If undetected and untreated, inherited heart conditions, can be deadly and they continue to devastate families, often by taking away loved ones without warning," said BHF medical director Professor Sir Nilesh Samani.
Each week in the UK around 12 seemingly healthy people aged 35 or under are victims of sudden cardiac death with no explanation, largely because of these inherited conditions.
BHF-funded research has helped identify many of the faulty genes behind inherited heart conditions, which has led to the development of genetic testing services for those at highest risk for some of them, but more research is urgently needed for improved detection methods and treatment, the charity noted.
"We urgently need to fund more research to better understand these heart conditions, make more discoveries, develop new treatments and save more lives," said Prof Samani.