Researchers seeking to cure crippling diseases like arthritis and multiple sclerosis in humans say they've taken an early, important step by isolating the gene that causes a form of arthritis in mice.

"We are on the way to finding the cure for this type of arthritis in mice," Tariq M. Haqqi, a molecular biologist at the Mayo Clinic in Rochester, Minn., said Monday.

If the same kinds of arthritis-causing genes or inherited blueprints can be identified in humans, "we are one step closer to the cure and prevention of human rheumatoid arthritis and other human auto-immune diseases" in which the body apparently is attacked by its own disease-fighting immune system, Haqqi said.