Why longer telomeres may not always mean healthier for women’s reproductive health?
image: A simplified representation of the study basis. I, II, and III denote assumptions I, II, and III, respectively.
Credit: She, Jun-Sen; Liu, Rui; Mao, Su-Qing; Zhou, Bo-Kang; Wu, Xiao-Jing; Ding, Meng-Zhen; Wang, Ling-Xiang; Cao, Yi-Ning; Wu, Hai-Yan; Long, Yu-Hang; Guo, Fei; Huang, He-Feng; Gao, Ling.
Telomeres are often described as the protective caps of our chromosomes. Over time, telomeres get shorter, and this shortening has been linked to aging, infertility, and heart disease. For years, the common belief was: the longer the telomeres, the better. But a large new study led by researchers at Fudan University, China, discovered that longer telomeres may actually raise the risk of some common gynecological conditions.
Earlier studies hinted at a connection between telomere length and reproductive diseases, but the results were often contradictory. To cut through the confusion, researchers used a genetic method called Mendelian randomization (MR) to test cause-and-effect relationships without interference from other confounding factors.
By analyzing genetic data from nearly half a million individuals, they found that longer telomeres were causally linked to a higher risk of three common conditions: uterine fibroids, ovarian cysts, and endometriosis.
To check whether the diseases themselves might be altering telomere length, the researchers carried out a reverse MR analysis. This tested whether genetic risk for reproductive diseases could influence telomere length. The results were clear: none of the conditions, including the three previously linked with longer telomeres, had any causal impact on telomere length. This clear asymmetry in the findings solidifies the conclusion of a one-way causal relationship, where longer telomeres contribute to disease risk, but the presence of these diseases does not feed back to alter telomere length.
One theory is that longer telomeres allow uterine smooth muscle cells or endometrial cells to keep dividing when they should normally stop.“Our findings challenge the simple idea that longer telomeres are always protective,” said study author Dr. Ling Gao, the corresponding author. “In certain tissues, longer telomeres may actually help abnormal cells survive and grow.”
This is the first large-scale genetic study to establish a causal link between telomere length and these three reproductive diseases. The study suggests a possibility that telomere length could become a useful biomarker, helping researchers identify women at higher risk or tailor screening strategies more effectively.
Still, the authors caution that their findings are based on European genetic data and may not apply equally across all populations. Further research is needed to confirm the results and uncover the underlying biology.