The study will be reported in the February issue of the Journal of Bone and Mineral Research and is available online.
The gene, named CYP1A1, makes an abundant enzyme that detoxifies foreign substances and also breaks down estrogen as a normal part of maintaining proper estrogen balance. Within the general population, several variations of the CYP1A1 gene exist, and the variants differ from one another by one or more DNA base pairs.
"Previous studies showed that some CYP1A1 variants are linked to estrogen-related cancers, such as breast, ovarian or endometrial cancers," says Reina Armamento-Villareal, M.D., assistant professor of medicine in the Division of Bone and Mineral Diseases. "The link to estrogen suggested that the gene could also affect bone density. No one had ever investigated that possibility, so we set up a study to evaluate the relation between bone density and variations of the CYP1A1 gene."
The researchers studied 156 women with an average age of 63.5 years who were at least one year past menopause. They analyzed the genetic sequence of each woman's CYP1A1 gene to identify which of the genetic variants they possessed.
One of the variations of the gene, known to be present in 19 percent of the general population, was found in women who had significantly lower blood estrogen levels and higher levels of urinary estrogen breakdown products than normal. These women also had a higher than normal urinary concentration of a marker that indicates bone resorption and had significantly lower than normal bone density in regions of the upper femur near the hip joint.
Source:Washington University School of Medecine