If we do manage to identify the genes that provide a disease risk in OA, it will tell us a great deal about how the disease develops

Dr Madeleine Devey, Arthritis Research Campaign

Osteoarthritis (OA), which affects around 1m Britons, is caused by the degeneration of the cartilage - the protective material that stops bones rubbing together in the joints.

It mainly affects knees, hips and hands (the most common), as well as the foot and the neck & back (spondylosis), but does not affect other body tissues.

Researchers from the Boston University School of Public Health looked at DNA material for 793 older parents and 684 of their middle-aged children.

The parental group in the study had all been part of the Framlingham Study, a long-term study of OA, that began in 1948.

The average age was 62 for the parents and 54 for the children.

Half of the original participants and 30% of their offspring had at least one hand joint affected by OA.

Radiologists also looked at images of parents' hands and compared them to those of their children.

David Felson, professor of medicine at Boston University School of Medicine, who was one of the researchers, said: "It is significant in that our findings help us move forward in identifying regions of certain chromosomes which may harbour these genes.

"This will allow us and others to identify the genes that confer these increased risks.

"Once the genes are identified, treatments can be developed."

Gene search

Dr Madeleine Devey, scientific secretary of the Arthritis Research Campaign (ARC), said: "We have come a long way since OA was rather dismissed as inevitable "wear and tear" and have known for some time that at least some forms of the disease have a genetic component.

"This study is one of several ongoing at the moment that is trying to identify the genes that confer risk for disease."

An ARC-funded study has suggested several areas on different chromosomes containing potential susceptible genes for hip and knee OA.

Dr Devey added: "What is very interesting is that both the US and our studies point to different susceptibility genes in different types of OA - that is the genes conferring risk appear to be quite different for OA at different sites, hand, knee and hip.

"This underscores the very complex nature of OA."

She said studies like that carried out in the US were "a very important first step".

She added: "If we do manage to identify the genes that provide a disease risk in OA, it will tell us a great deal about how the disease develops, help in the design of therapies and identify people at highest risk - perhaps even leading to strategies to prevent the disease."

The research is published in the journal Arthritis & Rheumatism.