Victims may experience just a few fractures in a lifetime or several hundred beginning before birth. The number of Americans affected is unknown, but estimates range from 20,000 to 50,000. While the study is an important early step in the search for a cure, its immediate effect may be to exonerate an expanded group of parents whose children frequently appear in emergency rooms with unexplained fractures, and who may be accused of child abuse.
The study was led by Brendan Lee, M.D., Ph.D., associate professor of Molecular and Human Genetics at the Baylor College of Medicine. Brendan Boyce, M.D. professor of Pathology at the University of Rochester Medical Center, added expertise to the large, international research team in the analysis of skeletal defects caused by lack of effective function in the newly discovered gene.
Previously, OI was known only as a genetic disorder in the formation of collagen fibers, the protein framework of which bone and cartilage are built. People with OI were known to have a faulty gene that instructed their bodies to make either too little or weak collagen because of defects or mutations in one of the collagen genes, of which there are more than 20. The current study found a new gene, that when mutated, reduces the ability of a protein involved in collagen formation, called CRTAP (cartilage-associated protein), to guide collagen production as it forms the proper framework of bone.
"The study is important because it clarifies a new mechanism by which the OI can occur and makes possible new tests to identify affected children and provide them with added medical support," Boyce said. "There may be up to 15 percent of children with Brittle Bone Disease who have mutations related to the new gene. Although the number of affected children is small, the demonstration that they have an inherited form of OI could have a major impact on their future health and quality of life."
In the study, mice were genetically engineered by the Baylor team with the CRTAP gene removed, and then monitored for signs of abnormalities. Results showed that the mice were unable to properly line up the fibers that make up collagen using an enzyme called 3-prolyl hydroxylase, which they determined needs to bind to CRTAP for it to function normally. As a result of the loss of normal 3-prolyl hydroxylase function, the cells that build bone (osteoblasts) were found to make thicker collagen fibers, but fewer of them, resulting in weaker bone.
Boyce and his group in the Center for Musculoskeletal Research at the Medical Center characterized the skeletal abnormalities in the genetically engineered mice and carried out studies of bone cells from the mice as well as detailed microscopic analysis of their bones. They found that, without this key gene, mice developed osteoporosis due to defects in their osteoblasts. Another team working at McGill University in Montreal identified human patients who had OI due to mutations in CRTAP, demonstrating for the first time that CRTAP has an essential function in humans.
In addition, the findings of the current study provide the first proof that osteogenesis imperfecta can be inherited in a recessive manner. Previously, the genes known to be involved in OI were dominant, meaning that if you had a defect in the gene in your chromosome, you developed the disease. That left open the possibility that the mutation causing OI was spontaneous, that something went wrong for the first time in the gene of the person developing it, and not inherited from parents.
The newly discovered gene however is a recessive trait, signifying that the disease can be passed down generation to generation, with recessive forms accounting for recurrence. When each parent has one mutated gene and one normal gene, they have one-in-four chance of having a child with osteogenesis imperfecta.
Funding for the research came from the National Institutes of Health, the Baylor College of Medicine Developmental Disabilities Research Center, and the Shriners of North America. Others institutes participating were the Istituto Nazionale per la Ricerca sul Cancro in Genova, Italy, The Shriners Hospital for Children in Oregon, McGill University in Montreal and The University of Washington in Seattle.
"Beyond OI, there may be other connective tissue disorders caused by mutations in genes associated with 3-prolyl hydroxylation, a process that occurs in many types of tissues," Boyce said. "Current treatment for OI does not cure the disease and is designed to reduce the risk of fracture. Only through a better understanding of the disease at the genetic and protein level will we be able to someday offer something better."
Greg Williams | EurekAlert!
Bacteria as pacemaker for the intestine
22.11.2017 | Christian-Albrechts-Universität zu Kiel
Researchers identify how bacterium survives in oxygen-poor environments
22.11.2017 | Columbia University
The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.
Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.
During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....
The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.
Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
22.11.2017 | Business and Finance
22.11.2017 | Physics and Astronomy
22.11.2017 | Physics and Astronomy