A reason why millions worldwide fall prey to the painful joint condition gout may have been uncovered.
Gout can be disfiguring and painful
A rise in UK gout cases has been blamed on increasingly unhealthy lifestyles.
However, genetic analysis of more than 12,000 people, published in the journal Nature Genetics, has found that a gene variant may also raise the risk.
Researchers at the MRC Human Genetics Unit, in Edinburgh, said the gene, and the protein it controls, might one day be targeted by new gout drugs.
In a healthy body, uric acid, a waste product found in the blood, is removed by the kidneys and passes out of the body in urine.
However, in some people the kidney cannot get rid of it properly and it builds up in the blood, forming crystals in the joints, leading to inflammation, stiffness and pain.
Various food types have been blamed, with the consensus that diets rich in refined sugars, protein and alcohol increase the risk.
Many thousands of people have a diet which appears to increase the risk of gout, but far fewer actually develop the illness.
Now scientists at the MRC Human Genetics Unit may have worked out why that is.
The gene variation they found, in the SLC2A gene, appears to make it harder for the body to remove uric acid from the blood.
Testing and treatment
Professor Alan Wright, who led the research, said: "The gene is a key player in determining the efficiency of uric acid transport across the membranes of the kidney."
His colleague Harry Campbell said: "Some people will have higher or lower risk of gout depending on the form of the gene they inherited.
"This discovery may allow better diagnostic tools for gout to be developed."
At the moment, drug treatment for patients is limited.
Although gout is a disease more usually found in a historical textbook, it is estimated that one million people in the UK suffer from it in some form.
Professor Stuart Ralston, from the British Society for Rheumatology, said that he often came across patients whose lifestyles did not fit the traditional view of over-consumption.
"Until recently you would associate gout with boozing and rich food, but there are plenty of other patients who are quite abstemious. This might be a genetic marker for gout risk.
"What is exciting is that it could be a target for new gout drugs."
Dr Andrew Bamji, president of the British Society for Rheumatology, said that the research supported a recent study which suggested that too many sugary soft drinks could trigger gout.
He said: "It appears that this gene also plays a role in the control of levels of fructose sugar in the body, which would explain the finding that soft drinks were linked to attacks."