We tend to think of menopause as coming hand-in-hand with hot flashes and night sweats. Not all women experience these symptoms, however, which led researchers to question whether genes could be a determining factor.
Gene variants affect a receptor in the brain that regulates estrogen release and is present across all ethnicities, according to the team from UCLA. It appears that women who have these variants are more likely to have hot flashes than women who lack them. The study — which was published last week in Menopause, the peer-reviewed journal of the North American Menopause Society — may potentially lead to new treatments to relieve symptoms.
"No previous studies have focused on how variants in women's genes may be linked with hot flashes, and these results were highly statistically significant," said Dr. Carolyn Crandall, professor of medicine in the division of general internal medicine and health services research at the David Geffen School of Medicine at UCLA, and the study's principal investigator. "These associations were similar across European American, African American and Hispanic American women, and they persisted even after we accounted for other factors that might influence hot flashes."
According to the study, more than 70% of women experience hot flashes and night sweats, which are known as menopausal vasomotor symptoms. Ethnicity has been linked to an increased risk for frequent vasomotor symptoms, as have greater body mass index, lower education level, smoking, anxiety and depression. But genetic links to these symptoms have remained unclear.
The researchers performed a study that looked at common genetic variations across the entire human genome to find links between variations in genes and observable traits — in this case, hot flashes and night sweats. They examined data from 17,695 postmenopausal women ages 50 to 79 years who participated in the Women's Health Initiative and who provided DNA samples and information about whether they had experienced hot flashes or night sweats. The researchers examined more than 11 million gene variants, called single-nucleotide polymorphisms, sampled across the entire genome.
They found that 14 of the variants were associated with experiencing hot flashes. All of them were located on chromosome 4. Specifically, the gene variants are located in the part of chromosome 4 that encodes the tachykinin receptor 3. This receptor is located in the brain, where it interacts with nerve fibers that regulate estrogen hormone release. For example, women with mutations in the receptor 3 gene are infertile. This is the first human study, according to the team, linking tachykinin receptor 3 gene variants with hot flashes.
Crandall noted that the researchers cannot determine how environmental factors might have influenced the results. Additionally, they may have been unable to detect other, rare gene variants that could also affect hot flashes. Because this is the first report of its kind in humans, the results should be confirmed in future studies that would help scientists better understand exactly how they may affect hot flashes.
"If we can better identify what genetic variants are associated with hot flashes, this could lead to novel treatments to relieve them," Crandall said.