What you carry at this position in your DNA and what research says about it.
Menopause and Fibroid Risk: 10/10 evidence, 30 publications.
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Sample genotype (not yours): G/G
Earlier Menopause and Typical Fibroid Risk
This genotype is linked to an earlier onset of natural menopause, potentially shortening the reproductive window. However, it is also associated with a lower, typical risk of developing uterine fibroids and breast cancer.
What this genotype means: Earlier natural menopause; Typical risk of uterine fibroids; Typical risk of breast cancer.
Sample genotype (not yours): A/A
Delayed Menopause but Higher Fibroid Risk
This genotype significantly delays natural menopause by nearly two years, extending fertility. However, it also carries a substantially higher risk of developing uterine fibroids and breast cancer.
What this genotype means: Menopause delayed by ~22 months; Higher risk of uterine fibroids; Higher risk of breast cancer.
Sample genotype (not yours): G/A
Slightly Delayed Menopause and Intermediate Fibroid Risk
Carrying one copy of the A allele is associated with a modest delay in the onset of natural menopause by about 11 months. This benefit is accompanied by a slight increase in the risk of uterine fibroids and heavy menstrual bleeding.
What this genotype means: Menopause delayed by ~11 months; Slightly higher risk of uterine fibroids; Slightly higher risk of heavy bleeding.
Gene function and biological role
Gene Function: The MCM8 gene plays a vital role in DNA double-strand break repair and homologous recombination [1]. It is highly expressed in oocytes and is essential for normal ovarian development and maintaining the ovarian reserve [1]. Genetic variations in this gene are heavily implicated in reproductive aging and the timing of natural menopause [1]. Additionally, MCM8 is linked to hormone-related conditions, sharing genetic pathways with uterine fibroids and breast cancer [2] [3].
Variant Impact: The rs16991615 variant is a missense mutation in exon 9 of the MCM8 gene, resulting in a glutamate-to-lysine amino acid change. This molecular change alters the function of the MCM8 protein, affecting DNA repair efficiency and ovarian follicle depletion rates [1]. The variant allele is strongly associated with a delayed age at natural menopause, extending the reproductive lifespan [4]. However, this same genetic change also increases susceptibility to hormone-driven conditions like uterine fibroids [5] and breast cancer [6].
Key Insight: The same genetic variant that delays menopause and extends fertility also increases the risk of developing uterine fibroids and breast cancer.
Location: MCM8. Chromosome 20 · 20p12.3 · 6.0 Mb
Estimated prevalence by population
Global 92.0%; European 88.1%; African 97.8%; East Asian 100.0%; South Asian 95.7%; Americas 89.0%; Ashkenazi 80.9%; Finnish 96.6%; Middle Eastern 91.4%; Amish 92.3%.
Estimated GG genotype frequency.
Global 7.8%; European 11.5%; African 2.2%; East Asian 0.0%; South Asian 4.3%; Americas 10.6%; Ashkenazi 18.1%; Finnish 3.3%; Middle Eastern 8.4%; Amish 7.6%.
Estimated GA genotype frequency.
Global 0.2%; European 0.4%; African < 0.1%; East Asian 0.0%; South Asian < 0.1%; Americas 0.3%; Ashkenazi 1.0%; Finnish < 0.1%; Middle Eastern 0.2%; Amish 0.2%.
Estimated AA genotype frequency.
Showing effects for G/G genotype
Endocrine & Reproductive
Menstrual, Menopause & Ovarian Traits
Age at Menopause. Evidence: 10/10. Source: PMID 22267201. Earlier Menopause.
Heavy Menstrual Bleeding. Evidence: 8/10. Source: PMID 31649266. Typical.
Female Reproductive Health & Fertility
Uterine Fibroids. Evidence: 10/10. Source: PMID 30194396. Typical Risk.
Cancer & Oncology
Breast Cancer
Breast Cancer. Evidence: 8/10. Source: PMID 29059683. Typical Risk.
Showing effects for A/A genotype
Age at Menopause. Evidence: 10/10. Source: PMID 22267201. ~22 Months Later.
Heavy Menstrual Bleeding. Evidence: 8/10. Source: PMID 31649266. Increased Risk.
Uterine Fibroids. Evidence: 10/10. Source: PMID 30194396. Increased Risk.
Breast Cancer. Evidence: 8/10. Source: PMID 29059683. Increased Risk.
Showing effects for G/A genotype
Age at Menopause. Evidence: 10/10. Source: PMID 22267201. ~11 Months Later.
Heavy Menstrual Bleeding. Evidence: 8/10. Source: PMID 31649266. Slightly Increased.
Uterine Fibroids. Evidence: 10/10. Source: PMID 30194396. Slightly Increased.
Breast Cancer. Evidence: 8/10. Source: PMID 29059683. Slightly Increased.
What this genotype means for the people who carry it
Sample genotype: GG (Homozygous)
Having two copies of the G allele is the most common genetic profile globally. This genotype is associated with a higher likelihood of undergoing earlier natural menopause, with studies indicating an increased chance of menopause occurring before age 46 [1]. The earlier onset of menopause is driven by a faster rate of ovarian follicle depletion [2]. On the positive side, because this genotype does not carry the risk-increasing A allele, it is associated with a typical, baseline risk of hormone-sensitive conditions [3]. Specifically, these individuals have a lower risk of developing uterine fibroids compared to carriers of the A allele [4]. They also maintain a standard baseline risk for breast cancer [5].
Earlier natural menopause; Typical risk of uterine fibroids; Typical risk of breast cancer.
Sample genotype: AA (Homozygous)
Having two copies of the A allele presents a clear genetic trade-off between reproductive longevity and disease risk. On one hand, this genotype delays natural menopause by an average of 22 months, preserving ovarian function and fertility for longer [1]. This is reflected in significantly higher levels of anti-Müllerian hormone and a larger follicle count [2]. On the other hand, the prolonged hormonal exposure and altered DNA repair efficiency significantly elevate the risk of uterine fibroids [3]. It is also associated with a higher risk of heavy menstrual bleeding [4]. Furthermore, these individuals have an increased risk of breast cancer, with an odds ratio of approximately 1.1 [5].
Menopause delayed by ~22 months; Higher risk of uterine fibroids; Higher risk of breast cancer; Higher risk of heavy menstrual bleeding.
Sample genotype: GA (Heterozygous)
This heterozygous genotype represents a biological middle ground for reproductive aging and hormone-related risks. Carrying a single A allele delays the onset of natural menopause by an average of 11 months, extending the active reproductive lifespan [1]. This delay is supported by higher circulating levels of anti-Müllerian hormone, which indicates a larger ovarian reserve [2]. However, this extended exposure to estrogen and other hormones slightly increases the risk of developing uterine fibroids [3]. It is also associated with a modest increase in the likelihood of experiencing heavy menstrual bleeding [4]. Additionally, there is a very slight increase in breast cancer susceptibility compared to the G/G baseline [5].
Menopause delayed by ~11 months; Slightly higher risk of uterine fibroids; Slightly higher risk of heavy bleeding.
Variants with shared genetic architecture
rs1056827 · CYP1B1 Gene · Chr 2 · Breast Cancer Risk
rs1799949 · BRCA1 Gene · Chr 17 · BRCA1 Cancer Risk
rs10759243 · RNU6-996P Gene · Chr 9 · Breast Cancer Risk
Association analysis identifies 65 new breast cancer risk loci.
A genome-wide association study of early menopause and the combined impact of identified variants.
Content updated August 2026.
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