Genetics means some women on bisphosphonates are more likely to fracture

A small percentage of older women who take bisphosphonates for osteoporosis are more likely to suffer a type of fracture in their femur (upper leg bone). Now a new study on 101 deceased baboons explains that this could be because of genetic variation.

Baboons are very similar to humans and develop some of the same age-related diseases. Their bones were examined under a microscope (they had died for reasons unrelated to the research project). Differences were found in bone remodelling (when mature bone tissue is removed from the skeleton so that new tissue can be added) that were because of inherited differences in the animals.

In osteoporosis, bone remodelling happens faster than the growth of new bone tissue to replace the lost bone. Bisphosphonates suppress remodelling, allowing the accumulation of bone tissue.

 “The results of this study suggest an explanation for why some women respond differently to the widely prescribed bisphosphonates,” says Dr Lorena Havill who led the work. “This supports the potential for a scenario in which certain individuals who are genetically predisposed to cortical microstructure that is less mechanically advantageous may experience disadvantageous responses to remodelling suppression, such as being at higher risk for atypical femoral fractures.”

So some women are genetically more likely to have slower remodelling in the absence of osteoporosis. This could cause the drugs to have a greater effect on them and weaken their bones in areas not typically prone to osteoporotic fractures.