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Last Updated: Thursday, 11 October 2007, 23:09 GMT 00:09 UK
Hunt for osteoarthritis gene link
Osteoarthritis of the knee
Osteoarthritis commonly affects the knee joint
British researchers are to carry out the first study to seek to uncover the genetic causes of osteoarthritis.

The analysis of DNA from 14,000 volunteers could lead to a simple test for predicting who is at risk from severe forms of the disease.

And it is hoped the 2.2m research project will identify new targets for treatment to reduce the need for joint replacement surgery.

Osteoarthritis affects more than two million older people in the UK.

The condition causes pain and stiffness as the cartilage at the ends of bones is lost.

We are dealing with a major genetic disease - two and a half times more heritable than breast cancer
Professor Tim Spector

There are no effective drug treatments to control the progression of the disease and currently available painkillers carry a high risk of side-effects.

Around 120,000 knee or hip joint replacements are carried out each year in the UK - a figure which is expected to increase as people live longer.

Eight centres across the UK are taking part in the two-year project, which will use DNA samples from 8,000 osteoarthritis sufferers and compare them with 6,000 healthy volunteers.

The 30 genetic scientists involved in the study will scan the whole genome to look for genetic mutations that occur more frequently in people with the disease.

Cheap test

It is hoped that within a few years, a "suite" of genes will be identified that can be used to test who is likely to develop the most severe, progressive form of the condition.

Such a test would be cheap - costing under 10 - and would help doctors and patients decide how best to stop the disease from progressing.

Intensive early treatment and healthier living through exercise or losing weight may help those at most risk hold the disease back, the researchers said.

It is likely that the study will identify pathways not yet known to play a part in osteoarthritis, giving researchers the chance to develop new treatments.

Professor Tim Spector, genetic epidemiologist from St Thomas's Hospital, London, and a member of the research consortium, said: "We are dealing with a major genetic disease - two and a half times more heritable than breast cancer."

He said they expected to find hundreds of genes which increase susceptibility to the condition, not just one or two.

Although environmental and lifestyle factors also have a role in the development of the condition, it is likely a range of genes act together to increase a person's susceptibility.

It is estimated that at least 50% of knee osteoarthritis and 60% of hip osteoarthritis is genetic.

"Most people end up getting osteoarthritis but only a third end up getting it severely and these are the people that are going to end up with expensive joint replacements.

"These genes can tell us who is going to do badly."

The trial, known as arcOGEN, is being funded by the Arthritis Research Campaign.

Professor Alan Silman, medical director of the Arthritis Research Campaign, said osteoarthritis was the most important cause of disability in the elderly.

"There aren't any current treatments, apart from symptomatic treatments, so the key thing is to identify the cause."



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