In 1994, an athletic man we'll call John was involved in a car crash. He was uninjured, and X-rays of his spine showed no fractures. They did, however, reveal unusually dense bones. John's radiologist referred him to Karl Insogna, the director of the Yale Bone Center. "His bone density was eight times higher than average for a man his age," Insogna recalls. This fact may not have surprised John, who used to sink like a stone when he tried to swim. Unable to determine a diagnosis or any negative symptoms, Insogna sent John on his way.
Six years later, Insogna heard a fellow physician mention he'd seen a family with very high bone mass. Together they traced the family tree, linking John to an extended kin group sprinkled up and down the Eastern seaboard. The affected kin all had very dense bones and unusually square jaws, but otherwise normal skeletons. ...
