Rare mutations in a single gene are linked to lower cholesterol levels and a 50 per cent reduced risk of heart disease, research has shown.

Scientists believe the discovery might guide the way to new treatments.

The gene, known as NPC1L1, is already the target of one cholesterol-lowering drug, ezetimibe, which works in a different way from more widely prescribed statins.

Researchers found that people with one inactive copy of the gene − which normally works in pairs − seem to be protected against raised low-density lipoprotein (LDL), the harmful form of cholesterol that damages arteries.

The discovery might guide the way to new treatments

Nathan Stitziel, a member of the team from Washington University School of Medicine, US, said: “This analysis demonstrates that human genetics can guide us in terms of thinking about appropriate genes to target for clinical therapy.

“When people have one copy of a gene not working, it’s a little like taking a drug their entire lives that is inhibiting this gene.”

The study involved pooling together DNA study data from around 113,000 people. Of these, only 82 possessed a mutation that shut off one copy of the NPC1L1 gene. None of the participants had two inactive copies.

Roughly one in 650 individuals carry an inactive version of the gene, the scientists estimated.

The research, published in The New England Journal of Medicine, showed that people with just one working copy of the gene had LDL cholesterol levels 12 milligrams per decilitre lower on average than the average population.

This equated to a reduction of about 10 per cent − roughly the same level achieved by taking ezetimibe.

But those with inactive copies of NPC1L1 also had about half the risk of coronary heart disease as people with two functional copies.

Statins stop the body manufacturing its own cholesterol. In contrast, ezetimibe blocks absorption of cholesterol in the gut by inhibiting the protein made by NPC1L1.

While the drug is known for its cholesterol-lowering effect, the jury is out on whether it also reduces the risk of heart disease.