The finding was made when the senior investigators, Richard Lifton, M.D., chair of the Department of Genetics at Yale School of Medicine, and Karl Insogna, M.D., professor of internal medicine and director of the Yale Bone Center, identified a Connecticut family with bones so strong they rival a character in the recent movie, "Unbreakable." Osteoporosis is a loss of bony tissue that leads to fragile bones.
"If there are living counterparts to the character in Unbreakable, who is in a terrible train wreck and walks away without a single broken bone, its members of this family," Lifton said. "They have extraordinarily dense bones and there is no history of fractures. You find this maybe once in a million people."
Lifton said those family members with the genetic mutation have no symptoms. They do have a strikingly deep and wide jaw and bony growth on the palate. They also report trouble staying afloat when swimming.
Twenty members of the extended family helped in the genetic hunt by providing blood samples for DNA testing and most had their bone density measured.
Seven of the family members tested had extremely high bone density in the spine, the hip, and throughout their bodies, while nine of the family members had entirely normal bone density. Detailed serum and urinary biochemical measurements were performed in four of the participants with very high bone density. These were then compared with results from nine healthy control subjects.
"What we found is that the high bone density in this family behaved as a single gene disorder," Lifton said. "We then went on to map the location of the gene and identified the specific mutation responsible for the high bone
Contact: Jacqueline Weaver