Brittle bone disease protein identified

Scientists at the Baylor College of Medicine, University of Texas, have announced that discovery in mice could help to treat people with a form of brittle bone disease.

In the study, mice were bred with Osteogenesis Imperfecta (OI) and the activity of a protein which shapes and reshapes bones was monitored.

Scientists said intense activity of the protein in the mice was linked to OI.

They said the finding could lead to a new target for treatment, but experts warn the study is in mice and might not apply to humans.

Osteogenesis Imperfecta is an inherited condition, where abnormalities in the genes controlling collagen affect the bone’s strength.

In severe cases, people with OI can have between 200 and 300 fractures by the time they reach age 18, the Brittle Bone Society said. Current treatment is lacking.

Scientists looked at a protein in mice bred with the condition and compared them to “normal” mice.

They said the activity of transforming growth factor beta (TGF), which co-ordinates the shaping and reshaping of bone, was excessive in mice with OI.

When TGF was blocked with an antibody, the mice’s bones withstood “higher maximum load and ultimate strength” and showed “improved whole bone and tissue strength”, suggesting “resistance to fracture”, the study said.

Research was published in the journal Nature Medicine.

Dr. Brendan Lee, professor of molecular and human genetics at Baylor College of Medicine, said the study could “move quite quickly” into humans, and be at a clinical trial stage later this year, or early next year.

A pharmaceutical company in the US was looking at the pathway of TGF in other diseases, such as kidney disease, which could accelerate the trials, he said.

One mechanism behind the findings could be that the disruption of TGF meant the bone was absorbed in the body more quickly than it was made.

Dr. Brendan Lee added: “We now have a deeper understanding for how genetic mutations that affect collagen and collagen processing enzymes cause weak bones.”

He said the treatment appeared “even more effective” than other existing approaches.