A groundbreaking study has revealed that embryos from women with polycystic ovary syndrome (PCOS) carry a unique epigenetic memory, potentially explaining the inherited nature of this common reproductive disorder.
Presented at the 41st Annual Meeting of the European Society of Human Reproduction and Embryology (ESHRE), the findings highlight how early molecular changes may influence health outcomes before implantation even begins.
PCOS affects approximately 1 in 10 women of reproductive age and is characterized by hormonal imbalances, irregular periods, and ovarian cysts. While widely recognized as a cause of infertility, its underlying mechanisms have remained elusive—until now.
Led by Dr. Qianshu Zhu, researchers analyzed oocytes and early embryos from 133 PCOS patients and 95 non-PCOS women undergoing fertility treatments. Using advanced sequencing technology, the team identified widespread disruptions in gene activity and epigenetic regulation in embryos from PCOS-affected women.
The study focused on three key histone marks—H3K27me3, H3K4me3, and H3K9me3—which control gene expression during early development. Crucially, nearly half of the abnormal H3K27me3 patterns seen in embryos were already present in the mother’s egg cells, indicating that epigenetic signals are transmitted from mother to child before conception is complete.
Further, these changes disrupted genes involved in genome activation, metabolism, and chromatin organization, and even affected retrotransposons, mobile DNA elements normally kept in check to maintain genetic stability.
In a promising turn, researchers found that treating affected embryos with PRC2 inhibitors—specifically EED226 and valemetostat—reduced abnormal histone patterns and partially restored normal gene activity. This opens the door for potential therapeutic strategies to correct epigenetic imbalances at the earliest stages of life.
“This could revolutionize how we assess embryo health and PCOS risk,” said Dr. Zhu. “We’re seeing a molecular footprint of PCOS before the embryo even implants.”
Currently, PCOS is diagnosed through hormone testing and imaging of ovarian cysts. However, this research suggests that epigenetic profiling—especially tracking H3K27me3—could become a powerful new tool in identifying and possibly preventing PCOS in the next generation.
Dr. Zhu emphasized the preliminary nature of the study, noting that long-term effects on children have not yet been demonstrated. The next phase will involve mouse model experiments targeting genes (Kdm6a and Kdm6b) that regulate H3K27me3, to determine whether altering these marks influences PCOS traits in offspring.
“If we can confirm that changing these epigenetic markers modifies disease risk in the next generation, we’ll be much closer to preventing PCOS before it starts,” he said.
Prof. Dr. Karen Sermon, Chair of ESHRE, welcomed the findings, stating, “PCOS remains one of the major unsolved mysteries in reproductive medicine. These insights into embryonic epigenetics represent a major step forward.”
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