Genetic Differences Exist in Early Knee Osteoarthritis

Patients with radiographic signs of early knee osteoarthritis are genetically different from those without radiographic signs of the disease.

Patients with radiographic signs of early knee osteoarthritis are genetically different from those without radiographic signs of the disease, according to additional research released by Interleukin Genetics, Inc. and the Thurston Arthritis Research Center at the University of North Carolina at Chapel Hill.

The findings also demonstrate that these patients progressed to moderate or severe OA at a much greater frequency. The 1,154-patient longitudinal study evaluated the role of genetic factors in osteoarthritis (OA) progression.

In current clinical settings, patients with early radiographic signs of knee osteoarthritis as often determined by the Kellgren-Lawrence grading scale (grades 0 - 4, with 0 being normal and 4 severe OA) are typically considered non-diseased. As a result, patients with early-stage osteoarthritis may not receive adequate medical management to avoid pain and disability associated with disease progression. These new findings could enable at-risk patients to receive critical early intervention to offset complications associated with moderate and severe disease.

“Patients with early osteoarthritis are frequently classified as ‘healthy controls’ in disease-related clinical research studies. This new information should allow more explicit identification of truly healthy subjects and should also allow identification of early disease patients who may benefit from new drugs in development to modify the progression of OA,” said Dr. Ken Kornman, PhD, Chief Scientific Officer, Interleukin Genetics, Inc, in a press release.

The findings are the result of an analysis study participants in the Johnston County Osteoarthritis [JoCO OA] Project, led by Dr. Joanne Jordan, the Herman & Louise Smith distinguished professor of medicine and chief, Division of Rheumatology, Allergy, and Immunology at the Thurston Arthritis Research Center of the University of North Carolina at Chapel Hill. Participants were examined for OA and monitored for a period between four and 11 years to study changes in disease characteristics. Subjects at the start of the study were analyzed for genetic markers.

“This is the first study to suggest that people with possible early knee OA on their x-rays, are genetically distinct from those with no x-ray signs of knee OA. This reinforces the idea that these people actually have early OA and should be targeted for early intervention,” Jordan said.

Of those individuals who were completely free of radiographic signs of knee osteoarthritis at the onset of the study, only 8.5 % progressed to moderate or severe disease, whereas 33 % of those with very early radiographic signs of disease exhibited progression. Those with early signs of OA were more likely than those who had no signs of disease to carry certain genetic factors, including variations in both the IL-1 receptor antagonist gene (IL1RA) and the DVWA gene that is involved in collagen formation. Both genes have been previously associated with susceptibility to knee OA and progression to severe disease. The combination of early radiographic signs of disease and carriage of gene variations associated with OA progression appears to identify individuals at increased risk for severe OA.

Source: Interleukin Genetics, Inc

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