Characterizing the Effects of Fragile X Mental Retardation (FMR1) Deletion in Mice

Fragile X syndrome (FXS) is a genetic disorder characterized by hyperactivity and intellectual disability. FXS is the result of FMR1 gene inactivation on the X chromosome. FMR1 encodes for FMR protein, which likely plays a role in mRNA translation in the brain and is essential for normal cognitive development. Preliminary data shows that mice with FXS have high bone density; however, it remains unclear which bone cells are contributing to this increase and which FMR1 associated genes are affected. The objective of this study is to examine the effects FMR1 deficiency has on the skeletal system; specifically, what cells and genes are affected by this deletion. To test this hypothesis, osteoclasts (bone-resorbing cells) were quantified in mice with FMR1 deletion and compared to their control group using histomorphometric technique via Osteomeasure high-resolution digital video system. In addition, the relationship between FMR1 and associated genes were studied by isolating RNA from cells and bone tissue harvested from young mice to test for levels of gene expression with quantitative PCR. These results will prove whether osteoclasts contribute to the increase in bone mass in mice with FMR1 deletion and if the associated genes are altered in the absence of FMR1.