I run a UK-wide study intended to characterise patients with very dense bones, and to identify genetic abnormalities which underlie these. Understanding the causes of high bone mass may help us to identify new ways of treating conditions associated with reduced bone mass, like osteoporosis. This study may also help to shed new light on the cause of other conditions where excess bone occurs, such as osteoarthritis, in which new bone is produced in the form of osteophytes at the edges of worn out joints.