Genetic clues linking reproductive function and metabolic health

A study published in Nature Genetics expanded the number of genetic loci associated with polycystic ovary syndrome (PCOS) from 16 to 29. The analysis combined genomic data from 20,818 patients and 523,695 controls, for a total of 544,513 people. Separate analyses of plasma proteins and genetic risk in women and men point to links between reproductive hormone regulation and metabolic disease.

PCOS is a reproductive endocrine disorder characterized by excess androgens, infrequent or absent ovulation, and polycystic ovarian morphology. Under the Rotterdam diagnostic criteria, at least two of these features must be present. PCOS is a major cause of anovulatory infertility and is also associated with insulin resistance and type 2 diabetes. Previous genetic studies had suggested connections among brain, metabolic, and gonadal function, but the small number of identified loci limited investigations into the underlying biology and long-term health effects.

Shared findings and sex differences in genomic and protein analyses

Using a genome-wide association study (GWAS) meta-analysis, the researchers identified 29 independent genetic loci associated with PCOS. Thirteen were newly reported. Findings involving the follicle-stimulating hormone receptor gene FSHR and the sex hormone-binding globulin gene SHBG support a role for hormone regulation. However, finding an associated locus does not by itself establish a causal function for the gene involved.

Several PCOS risk variants were also associated with later age at natural menopause. The researchers interpreted this as suggesting that the number of eggs and follicles available over a lifetime, along with hormone regulation, may contribute to PCOS. The specific mechanism linking follicle depletion to reproductive lifespan remains to be tested in future work.

Plasma proteins were analyzed separately from the GWAS in about 22,000 women, and 31 proteins were associated with ovarian dysfunction. These included PCSK9, which is involved in lipid metabolism, and the low-density lipoprotein receptor (LDLR). The assessment covered category E28 of the International Classification of Diseases (ICD-10), which includes PCOS but is not limited to it, so these findings are difficult to interpret as the discovery of PCOS-specific biomarkers.

In a UK Biobank dataset independent of the GWAS discovery sample, the researchers analyzed a polygenic risk score (PRS) comprising about 1.12 million variants. Higher scores were associated with obesity, type 2 diabetes, and coronary artery disease in both women and men, but the patterns differed by sex. Higher scores were associated with higher total testosterone in women and lower total testosterone in men. For scores derived from a GWAS adjusted for body mass index (BMI), the association with type 2 diabetes remained in both sexes, whereas the association with coronary artery disease was significant only in women. The findings in men indicate that the related genetic predisposition is associated with other health measures, rather than indicating PCOS occurrence in men.

What needs validation before clinical use

The study strengthens the basis for examining PCOS reproductive and hormonal features alongside metabolic health. In a hospital biobank in Copenhagen, Denmark, a higher PRS was associated with female infertility after adjustment for age and BMI. By contrast, no clear association was found between genetic predisposition and childlessness or the final number of children. These population-level findings cannot predict an individual’s chances of becoming pregnant.

Ninety-three percent of GWAS participants were of European ancestry, and the women in the protein analysis had a mean age of 56.5 years; most were assessed after their reproductive years. Mendelian randomization analyses aimed at inferring causality also had limited statistical power because they used few genetic variants, and some outcome datasets combined women and men. These limitations make it difficult to treat genetic associations or the researchers’ mechanistic interpretations as established causes. The study also did not test whether PRS-based screening or personalized treatment improves patient outcomes.

Sources: Nature Genetics paper, public full text reviewed.