Genetics 'can influence osteoarthritis patients' sensitivity to knee pain'

People with knee osteoarthritis may experience different levels of knee pain based on their genetics, according to a new study.

Conducted by Penn State University in the US, the research came as part of a larger study assessing how arthritis affects the daily lives of patients and their families, specifically examining its impact on mood and interactions with partners.

A total of 120 knee osteoarthritis patients went through a 22-day assessment in which they wore an accelerometer to measure daily physical activity and reported on their pain three times a day. Greater pain variability throughout the day reflected increased sensitivity to pain after physical activity.

Genetic data was also collected from patients to determine if there were any associations with daily knee pain sensitivity, with results published in the Scandinavian Journal of Pain showing that two specific genes – COMT and OPRM1 – both an effect.

The team predicted that patients with one or more copies of a certain allele in either COMT or OPRM1 would have greater pain variability and more pain after daily physical activity, but in fact the most pronounced pain results were seen among patients with two copies of a different allele.

Lynn Martire, professor of human development and family studies at Penn State University, said: "Our results showed that the genotypes that had increased pain sensitivity were the opposite of what we predicted, but the context and the design of our experiment are different from previous work."

If these preliminary findings can be confirmed by a larger study, it could potentially lead to the development of tailored activity programmes based on a person's specific genetic background.

Dr Katherine Free, our research liaison and communications manager, said: "Osteoarthritis occurs as a result of a number of factors, including genetics and environmental causes such as age, previous joint injury and obesity. We know that osteoarthritis can affect people differently, and two people with the same level of X-ray damage in their joints can experience different levels of pain. Our Arthritis Research UK Pain Centre, for example, is currently conducting research in this area.

"Genetics may play some part in these differences, as this study shows. Understanding why this is the case takes us a step closer to being able to provide tailored treatment and advice to individual patients."

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