Researchers said the gene had been hiding in plain sight in previous hunts for genes that influence cardiovascular risk.
The region of DNA where it was found had been implicated as being important in controlling blood lipid levels in a report from several members of the same research team in 2008.
But although this DNA region had many genes, none of them had any obvious link to blood lipid levels.
In a new paper in the journal Nature Genetics, a team from the University of Michigan and the Norwegian University of Science and Technology said that they zeroed in on the gene in an entirely new way.
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Most of what they found turned out to be already known to affect cholesterol levels and other blood lipids.
However, one gene, dubbed TM6SF2, was not on the radar at all. In a minority of the Norwegians who carried a particular change in the gene, blood lipid levels were much healthier and they had a lower rate of heart attack.
When the researchers boosted or suppressed the gene in mice, they saw the same effect on the animals' blood lipid levels.
This was confirmed by the observations of a team led by researchers Jonathan Cohen and Helen Hobbs, who propose a role for the gene in liver disease in the same issue of Nature Genetics.