Anyone who has seen the M. Night Shyamalan movie “Unbreakable” knows that the protagonist is literally unbreakable, meaning his bones are so strong that they never break. David Dunn, played by Bruce Willis, was even the sole survivor of a gruesome train crash that killed the other 132 passengers. Now, that seems like the stuff of science fiction or fantasy, but what if we told you that a similar condition exists in real life? A family in Connecticut carries a unique gene mutation that makes their bones eight times denser than normal. The “world’s densest bones” are also immune to fracture!
In 1994, a man got into a car accident which was serious enough to cause multiple fractures. However, he walked out of it without a single broken bone! When radiologists looked at the X-rays of his spine, they were dumbfounded to see abnormally dense bones. The man was then referred to the Yale Bone Center where director Karl Insogna found that the man’s bones were eight times denser than it should be for a man of his age. The news did not surprise the man who admitted that he has never been able to stay afloat in the water. Failing to detect any negative symptoms or produce a proper diagnosis, Insogna sent him home.
After six years, Insogna heard one of his colleagues mention a family that has unusually high bone density. After tracing the family tree, they found that the man from the accident is actually related to the family and that they all have extremely dense bones, square jaws, but overall normal skeletons.
After carefully studying the family’s condition, Insogna and his team made a connection between chromosome 11 and the high bone density. However, at that time, the team was unable to sequence the region of the chromosome. By then, other experts had started to look into chromosome 11. Case Western Reserve University’s Matthew Warman and his team discovered a gene mutation known as “LRP5.” They attributed low bone density to this mutation. Upon hearing about Warman’s research, Insogna wondered if the same mutation can also cause unusually high bone density. So, they focused their attention on LRP5, and as they expected, they found the mutation that causes super-dense bones.
Surprisingly enough, Mark Johnson of the Osteoporosis Research Center in Omaha had already discovered this mutation while studying a family with the same condition. They had found 21 family members, seven of whom had severely high bone mass in the hip, spine, and other parts of the body. Only nine of them were found to have normal bone density. According to their findings, the bone density comes from a gene disorder. After mapping the location of that gene, they discovered the specific mutation that caused bones to get several times denser than normal.
The study also found that the mutation actually disrupts the correct functioning of the Wnt signaling pathway, which results in rapid bone formation. Further research on the subject can also help scientists to develop a treatment and perhaps even prevention for osteoporosis.