Twin study says genes explain little of knee arthritis risk

A former Mayo Clinic rheumatologist says twin research shows knee osteoarthritis is driven more by weight, mechanics and metabolic factors than heredity. The finding matters because patients may have more control over their risk than they think.

Why it matters: - Twin research suggests heredity accounts for only a small share of knee osteoarthritis risk. - The finding points patients toward factors they can change, including weight, movement and metabolic health. - Dr. Nisha Manek says the result has not reached many patients, even though it could change how they think about the diagnosis.

What happened: - Dr. Nisha Manek, a rheumatologist who spent 12 years on the faculty at Mayo Clinic in Rochester, Minnesota, reviewed twin studies in London that examined knee X-rays in identical and non-identical women. - The research used twin comparisons to separate inherited risk from environmental influence. - The studies found that genetics contributed very little to knee osteoarthritis.

The details: - Identical twins share the same genes, while non-identical twins do not, which helps researchers test whether a condition is mainly inherited. - Manek said the researchers were asking whether the link between obesity and knee osteoarthritis came from shared genes or from factors that can be changed through weight and lifestyle. - Manek said the major contributors are weight, mechanics and metabolic factors. - Manek said the practical message is that many patients receive a diagnosis without a clear sense of what they can do next. - If patients believe the disease is written into their genes, Manek said, they may see no room for action. - The research referenced in the release is the 2003 paper by Manek, Hart, Spector and MacGregor in Arthritis & Rheumatism. - The release links to more information about Dr. Manek: more information

Between the lines: - Manek is pushing back against a common fatalistic view of knee arthritis. - Her message shifts attention from inherited blame to behavior, environment and metabolic health. - She also signaled caution around GLP-1 medications, saying they can buy a three- to six-month window but that the key question is what patients do during that time. - Manek said she is neutral to cautious on those drugs, does not prescribe them, and wants patients to focus on diet while the window is open. - Manek said her stance is often misread in both directions.

What's next: - Manek said the field needs more attention on the modifiable drivers of knee osteoarthritis. - She continues to work with a small number of clients on inflammation, environment and stress. - Manek left Mayo Clinic in late 2011 to study energy medicine and consciousness research from a physics perspective. - She is the author of Bridging Science and Spirit.