A PEDIGREED BABOON MODEL FOR THE GENETICS OF CORTICAL BONE MATERIAL PROPERTIES

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Until recently, a majority of studies of bone fracture resistance focused on bone mass. However, epidemiological studies now suggest that a significant proportion of fracture risk is independent of bone mass. In addition to the effects of age and sex, proxy measures of bone strength (e.g. bone mineral content and density) consistently show significant genetic effects. While genetic studies of bone material properties have been conducted in rodents, similar studies have not been done in humans or other primates. Substantial differences in fracture properties between other species and primates underscore the need for a genetically well-characterized non-human primate model for studies of the genetics of bone material properties. We propose to investigate the contribution of genes to cortical bone material properties, direct measures of bone quality that are essential aspects of a bone's structural integrity. The ultimate objective of the proposed study is to establish the baboon as a model for the genetic study of human bone material properties. Using data collected from the right femur of 100 pedigreed adult baboons, the specific aims of this project are to: 1) determine cortical bone tissue properties including elastic modulus, yield and ultimate strength, post-yield behavior, fracture toughness, and mineralization (ash fraction and microCT-determined bone mineral density) and determine the degree to which cortical bone density and mineralization (ash fraction) are correlated to cortical bone material properties; 2) characterize normal variation, including age and sex effects, on cortical bone material properties in the baboon; and 3) detect and quantify the proportion of variation in these properties that is due to the additive effects of genes. We will assess the relative magnitude of the effect of genes on cortical bone properties as determined in this project vs. trabecular bone material properties determined from other research.