Japanese Study Finds Arthritis Gene Link

A mutated gene that affects cartilage may also be strongly involved in a tendency to arthritis, Japanese researchers reported on Sunday.

Their findings could lead to new treatments for and a better understanding of the disease, which affects tens of millions of people around the world. “Osteoarthritis is the most common joint disease in humans, and it is a primary cause of decreased activity in daily living and quality of life after middle age,” the researchers wrote in their report, published in the journal Nature Genetics. “Osteoarthritis affects more than 5 percent of adults worldwide and more than 7 million individuals in Japan alone.” The gene, called asporin, affects the breakdown of cartilage — the primary cause of osteoarthritis, the team led by Shiro Ikegawa at Japan’s RIKEN research institute found. The study of more than 1,200 volunteers showed several mutations in the asporin gene were associated with arthritis. “Asporin … was expressed abundantly in knee and hip cartilage from individuals with osteoarthritis but was barely detectable in cartilage from unaffected individuals,” they wrote. “In two independent populations of Japanese individuals with knee or hip osteoarthritis, the mutant form of asporin was overrepresented, and its frequency increased with severity of disease.” Asporin helps make up the extracellular matrix, which is the connective tissue that surrounds and supports cells. It interacts with TGF-beta, key growth factor for cartilage. (Source: Nature Genetics, Reuters Health, January, 2005)