Arthritis. A gene for smooth-running joints.

A new study on page 265 of this issue suggests that a genetic defect in mice causes the joint's cartilage cells to pump insufficient amounts of pyrophosphate--a natural water softener--into the joint cleft, and this in turn leads to the formation of bony spurs that eventually stiffen the joints completely. Because humans have an almost identical gene, and disorders such as osteoarthritis also feature an abnormal outgrowth of bones, some arthritis researchers are hopeful that these new findings may point the way toward a new class of pyrophosphate-based drugs similar to the antiscaling chemicals in washing powders and toothpaste. But, as many of the researchers point out, the numerous roads that lead to human joint degradation make a single cure-all unlikely.