Shared genes may explain why endometriosis and fibroids often occur together
image: Colocalization analysis of shared genetic loci for EM and UL. Colocalization plots for rs2235529 at the WNT4 locus (A) and rs58415480 at the SYNE1 locus (B). Both loci demonstrate strong evidence for a shared causal variant.
Credit: Juan Chen; Li Tang; Li-Lan Zou; Chuan-Bo Zhou; Ling Yang; Yu-Qiang Zhang.
Endometriosis and uterine fibroids are common conditions that can cause pelvic pain, heavy or irregular bleeding, and fertility problems. Endometriosis occurs when tissue similar to the uterine lining grows outside the uterus, while fibroids are noncancerous tumors that develop from uterine muscle. Although the conditions are different, many women experience both, making diagnosis and treatment more complicated.
A study published in Reproductive and Developmental Medicine suggests that this overlap may reflect shared biology as well as similar symptoms. Researchers found that women with endometriosis were about four times more likely to also report uterine fibroids, even after accounting for factors such as age and body mass index.
“Endometriosis and uterine fibroids are often approached as separate diseases, but our findings suggest that their connection may extend from clinical symptoms to underlying genetic mechanisms,” said corresponding author Yu-Qiang Zhang.
The team combined health information from 1,466 women with large genetic datasets and gene-expression data from diseased tissues. Rather than examining every laboratory detail separately, the researchers looked for genetic regions associated with both conditions and then asked whether the implicated genes were unusually active in endometriosis and fibroid tissue.
The analysis highlighted two shared genetic regions linked to WNT4 and SYNE1. WNT4 showed the clearest biological connection: its activity was increased in tissue from both conditions. The gene helps regulate reproductive development, cell growth and tissue organization. It was also associated with processes involving collagen and tissue remodeling, which are relevant because both endometriosis and fibroids involve abnormal tissue growth and fibrosis.
SYNE1 may also contribute to shared susceptibility, although its role is less clear and may involve regulation of other genes rather than changes in SYNE1 activity itself.
“WNT4 gives us a focused starting point for investigating why these conditions so often occur together, but further laboratory studies are needed before it can be considered a diagnostic marker or treatment target,” Zhang said.
The findings may encourage researchers and clinicians to view the two disorders more closely together. Greater awareness of their co-occurrence could help clinicians consider both conditions when symptoms overlap or continue despite treatment. In the longer term, understanding shared pathways could support more coordinated diagnostic strategies and therapies that address common disease mechanisms.
The study does not establish that the identified variants cause either condition. However, it provides a genetic framework for future research into more integrated and potentially targeted approaches to care.