Twins data links genes to chronic arthritis

Osteoarthritis - the commonest cause of joint pain in the elderly and of 50,000 hip and knee replacements a year - may have a significant genetic component, according to research published yesterday.

Between 39 and 65 per cent of the disease is inherited rather than the result of wear and tear, of sporting injuries or other environmental factors such as being overweight, a study involving 250 pairs of identical and non-identical twins suggests.

The discovery offers the prospect of identifying the gene responsible which in turn could lead to drug therapies which might replace many of the tens of thousands of joint replacements undertaken annually in people aged over 45.

The finding was described yesterday as "novel and exciting" by Dr Tim Spector, a consultant rheumatologist at St Thomas's Hospital, London, who said the disease remained "a massive problem in terms of the pain and suffering it causes".

One in three people eventually suffer some degree of osteoarthritis and one in six suffer significant pain and handicap from a condition which normally appears in the hands before progressing to the main joints. The aim now is to recruit 5,000 pairs of same-sex twins, both non-identical and identical, to identify the crucial gene.

To date, Dr Spector said, the joint disease, caused by the breakdown of the cartilage which covers bone endings, has been seen as the unglamorous result of wear and tear and football and work injuries. The twins study, however, shows that identical twins - who share all the same genes - are twice as likely to suffer the disease as non-identical twins, who share only half their genes.

"This should have a great impact on this often forgotten disease," he added. Identifying the gene would allow screeningwhile offering the hope in the longer term of new therapies.

Those with the gene, he said, could be given lifestyle advice - "keep your weight as low as possible, avoid marathon running, avoid orthopaedic surgeons doing anything to your cartilage, avoid too much football, but keep fit and keep your muscles strong". And in the longer run new drugs might be produced which would prevent the progressive development of the disease.

Wear and tear still remained an important factor, Dr Spector said, as did obesity, and both might prove of more importance in those already predisposed to the disease.

Gemini Research, a subsidiary of a company based in the British Virgin Islands, has bought the commercial rights to the twins' database. The company rather than donors will reap financial rewards if products are developed from the raw material they have provided.