Heart disease risk can be cut in half by a single mutation within a gene, according to new research.

The Niemann-Pick C1-like 1 (NPC1L1) gene is linked to high cholesterol levels. Ezetimibe, a commonly prescribed drug to lower blood cholesterol, targets this same gene.

Humans inherit two copies of each gene, with one of each coming from each parent. People born with just a single active copy of the NPC1L1 gene were found to be largely immune from coronary heart disease, a narrowing of arteries within the heart, which frequently leads to death.

So-called bad, or high LDL, cholesterol was also controlled in those with the mutation. Roughly one out of every 650 people, or about 0.15 percent of the population, lives with the unusual genetic structure. No subject in the study was found to have two inactive copies of the gene.

Levels of LDL cholesterol were 10 percent lower in those with an inactive copy of the gene, compared to the general population. This is roughly the same amount of protection provided by ezetimibe.

"Protective mutations like the one we've just identified for heart disease are a treasure trove for understanding human biology. They can teach us about the underlying causes of disease and point to important drug targets," Sekar Kathiresan from the Broad Institute and Massachusetts General Hospital said.

Statins reduce the amount of cholesterol produced by human bodies and are a more commonly prescribed class of drugs than ezetimibe. The drug functions by reducing the action of the NPC1L1 protein, which could account for the similar behavior in patients with one inactive gene.

Washington University School of Medicine researchers who worked with investigators from the Massachusetts Institute of Technology and Harvard University made the finding.

Researchers are still uncertain if ezetimibe is the best way to treat cholesterol levels, or if the usage of the drug helps to reduce the risk of heart disease.

"It's not possible to draw a direct conclusion about ezetimibe from this study. But we can say this genetic analysis gives us some confidence that targeting this gene should reduce the risk of heart attack. Whether ezetimibe specifically is the best way to target NPC1L1 remains an open question," Nathan Stitziel of the Washington University School of Medicine stated.

Ezetimibe and statins, which include Atorvastatin, sold under the brand name Lipitor and Simvastatin (Zocor), are sometimes prescribed in conjunction with each other to lower cholesterol.

Investigation of the relationship between NPC1L1 and heart disease was profiled in The New England Journal of Medicine.