A newly identified gene mutation helps explain a subset of cases of osteogenesis imperfecta (OI), or brittle bone disease, whose origin had until now remained mysterious. Identifying the new mutation is important because children with the disorder, whose bones break easily, are sometimes mistaken as victims of child abuse particularly those who do not carry the genetic mutation known to cause most cases of brittle bone disease.
Most cases of brittle bone disease are known to be caused by a structural change in a particular collagen protein. The new mutation responsible for up to 15 percent of cases acts differently and prevents collagen proteins from being properly modified after they are produced. The finding may also offer clues to the causes of as-yet-undescribed connective tissue diseases that may affect other parts of the body and gives insight into the basic mechanism of collagen formation, said the researchers.
In an article published in the October 20, 2006, issue of the journal Cell, Howard Hughes Medical Institute investigator Brendan Lee and his colleagues reported how mutations in a gene called cartilage-associated protein (CRTAP) can affect bone formation. Lee and his colleagues at the Baylor College of Medicine collaborated on the studies with researchers from Istituto Nazionale per la Ricerca sul Cancro in Italy, Shriners Hospital for Children in Canada, McGill University, Oregon Health & Science University, the University of Washington, and the University of Rochester Medical Center.
The long protein fibrils that make up collagen serve as a principal support for skin, tendon, bone, cartilage and connective tissue. Immediately after the collagen protein is manufactured by cells, it undergoes several biochemical modifications to transform it into functional fibers. One of the least understood of these modifications is the addition of a molecular unit called a hydroxyl group to the collagen protein. This
Contact: Jennifer Michalowski
Howard Hughes Medical Institute