Scientists say they have turned up a genetic clue that may help predict which people with knee osteoarthritis, or OA, are likely to see their disease progress.

The study, presented in 2010 at the World Congress on Osteoarthritis in Brussels, Belgium, involved data from the Johnston County Osteoarthritis Project, in North Carolina, which monitored 1,154 participants for up to 11 years to see when they got OA and how quickly it advanced.

Genetic tests were done on participants at the start of the study. In analysing those tests, researchers found nine genes associated with OA progression. The strongest association of the bunch involved a specific pattern of genetic variations in the interleukin-1 receptor antagonist, or IL-1Ra, gene.

These genetic factors nearly doubled the likelihood that a person’s OA would progress to a severe stage. Interleukin-1, or IL-1, is a chemical signal associated with inflammation and cartilage degradation.

“These genetic polymorphisms, which were previously found to be associated cross-sectionally with more severe knee OA, have now been shown to be associated with the development and progression or worsening of knee OA over time,” explains lead author Joanne M. Jordan, MD, director of the University of North Carolina’s Thurston Arthritis Research Center.

While researchers were able to see an association between these specific genetic variations and disease progression, they can’t explain why that is.

“It may have to do with the way molecules line up or fold or fit in their receptors, any of which can cause enzymes to behave differently from how they otherwise might,” Dr. Jordan says.

Dr. Jordan says more research is needed but she has hopes for what this discovery will mean down the road.

“This might make it possible to identify high-risk people in advance of getting OA or before it progresses,” she explains.