A groundbreaking study led by the University of Oxford’s Big Data Institute has revealed 25 genetic variants linked to infertility, alongside 269 variants connected to hormones that impact fertility. Published in Nature Genetics, this research is the first comprehensive analysis of the relationship between genetics and infertility, offering hope for improved diagnosis and treatments.
Infertility, affecting one in six couples worldwide, is influenced by a mix of genetic, environmental, and social factors. Yet for up to 28% of couples and 40% of women, the exact cause remains unknown. Previous studies have suggested hormonal imbalances and obesity as potential causes, but the genetic factors behind infertility have remained elusive until now.
The study identified 25 genetic variants associated with infertility, 22 of which were found in women and three in men. Additionally, it linked 269 genetic variants to hormones that regulate fertility, including follicle-stimulating hormone (FSH), luteinising hormone (LH), oestradiol (the primary estrogen in women), and testosterone. Despite these findings, no significant genetic link between female infertility and reproductive hormones was discovered, challenging previous assumptions.
For male infertility, three genetic variants were identified, one of which is near the ENO4 gene. This gene plays a role in sperm movement, and its removal in male mice leads to infertility. The study also found genetic associations between female infertility and endometriosis, while polycystic ovarian syndrome (PCOS) was linked to anovulatory infertility, where ovulation fails to occur. However, only three of the eight genetic variants related to anovulatory infertility were also associated with PCOS, suggesting that other factors may contribute to this condition.
The study also found no genetic link between obesity and infertility, contradicting prior research that suggested short-term weight loss could improve fertility in overweight and obese women. However, it did confirm a bidirectional relationship between obesity and anovulatory infertility, meaning each condition exacerbates the other.
Cecilia Lindgren, Professor of Genomic Endocrinology at Oxford, highlighted the importance of the findings, noting, “While specific genes related to hormone regulation may affect fertility, there is limited evidence for a strong genetic connection between reproductive hormones and infertility.” She emphasized the need for further research to explore other genetic and non-genetic factors that may influence fertility.
This study, which analyzed data from over one million participants across seven global population studies, is the largest of its kind. It represents a significant step forward in unraveling the complex biological factors behind infertility, offering new possibilities for treatment and support for those affected by this growing health issue.
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