Lessons for normal human biology often come from studying the abnormal. Consider the discovery of the mutated gene responsible for osteoporosis pseudoglioma, a rare condition that leaves bones so brittle that affected individuals are usually wheelchair-bound by their teenage years.
Beyond accounting for the disease, the gene "gives us insight into how bone mass accrues during growth," says Matthew L. Warman of Case Western Reserve University in Cleveland.
The gene and its protein, known as low-density-lipoprotein-receptor-related protein 5 (LRP5), may also inspire new ways to treat more-typical osteoporosis and other common bone diseases, suggests Warman. He unveiled the genetic finding last week at the American Society of Human Genetics Meeting in San Diego. The international team that has pursued the disease gene will detail the discovery next month in Cell.