New UK figures from the British Heart Foundation (BHF) show that double the number of people may be living with the deadly inherited gene which causes familial hypercholesterolemia (FH) than previously thought.
However, many of these people have not been identified - figures show that only around 20,000 people are being treated in specialist clinics for the condition.
If all of the estimated 250,000 people with the FH gene in the UK were identified and treated, as many as 25,000 deaths could be avoided, the BHF said.
It is now calling on NHS services across the country to urgently roll-out a nationwide testing programme for affected families.
FH is caused by a genetic fault that leaves people with dangerously high cholesterol from birth, significantly increasing their risk of a heart attack.
On average, FH can shorten life expectancy by 20 to 30 years if left untreated. Statins – which lower cholesterol – may be prescribed to adults or to children over ten who have the condition.
The BHF said the setting up of FH services has been slow in Scotland and England.
It is funding 25 FH nursing posts across 13 different locations to increase testing.