PARIS: The biggest probe yet into the inherited causes of osteoarthritis has turned up eight genes associated with this painful disease, bringing the tally of suspects to 11, The Lancet reported on Tuesday.

Researchers led by John Loughlin at Newcastle University, northeast England, compared the DNA code of more than 7,400 people with severe hip and knee osteoarthritis against that of more than 11,000 counterparts who did not have the disease.

The results were then cross-checked against a second group, comprising 7,500 people who had osteoarthritis and 43,000 otherwise healthy counterparts.

Osteoarthritis is the commonest form of arthritis, affecting about 40 per cent of the world's population aged older than 70.

Genes are believed to account for about half of the risk for the disease and environmental factors for the rest.

Spotting genes associated with disease helps identify people who are most at risk, so that they can make lifestyle changes. Genetic clues also open the way to new drugs to treat the condition.