rs9393800 — SYCP2L SYCP2L GWAS hit for age at natural menopause

SYCP2L rs9393800 — A Second Locus Hit That Shifts Your Ovarian Clock

Deep inside chromosome 6p24.2, a cluster of variants in and around the SYCP2L gene exerts some of the strongest genetic influences on when a woman reaches natural menopause. SYCP2L — synaptonemal complex protein 2-like¹¹ synaptonemal complex protein 2-like
a meiosis-specific structural protein that anchors chromosomes at centromeres during the first meiotic division in oocytes — plays a critical role in maintaining the primordial follicle reserve that determines reproductive lifespan. The rs9393800 variant is one of several genome-wide significant hits at this locus, each capturing a distinct aspect of SYCP2L regulation in the aging oocyte.

The Mechanism

rs9393800 sits within an intron of SYCP2L at GRCh38 position chr6:10,951,504. The variant is approximately 54 kb downstream of the rs9348724 regulatory site and 64 kb downstream of the rs2153157 splice-efficiency variant — all three map to the same functional gene but are not in complete linkage disequilibrium, meaning they can segregate independently. The biological pathway they share is the same: SYCP2L protein expression in oocytes determines how robustly centromeres are anchored during the prolonged meiotic arrest of primordial follicles.

Insufficient SYCP2L leads to progressive primordial follicle depletion. Female mice lacking SYCP2L protein undergo accelerated oocyte loss compared to wild-type controls²² accelerated oocyte loss compared to wild-type controls
Zhou et al. 2015, Hum Mol Genet 24:6505–6514, becoming subfertile earlier. At the clinical extreme, complete loss-of-function variants in SYCP2L cause premature ovarian insufficiency (POI) with secondary amenorrhoea and undetectable AMH before age 40, establishing the gene as essential for human ovarian longevity. The intronic rs9393800 variant likely influences SYCP2L expression through regulatory elements embedded in the intron, modulating the same oocyte survival pathway as the other locus variants through a partially independent mechanism.

The Evidence

The rs9393800-G association with earlier age at natural menopause was identified in the Day et al. 2015 meta-analysis³³ Day et al. 2015 meta-analysis
Large-scale genomic analyses link reproductive aging to hypothalamic signaling, breast cancer susceptibility and BRCA1-mediated DNA repair. Nat Genet 47:1294–1303, which reached a p-value of 4×10⁻¹³ with an effect estimate of −0.17 years per G allele — meaning each copy of the G allele is associated with approximately two months earlier menopause at the population level. This study was one of the first to show that menopause-timing loci cluster in DNA damage-response and meiotic recombination pathways, not just hormonal signalling — a mechanistic shift that placed oocyte genome maintenance at the centre of ovarian aging biology.

The 6p24.2/SYCP2L region was originally mapped to age at menopause in a 2009 GWAS of 17,438 women from the Nurses' Health Study and the Women's Genome Health Study⁴⁴ 17,438 women from the Nurses' Health Study and the Women's Genome Health Study
He et al. 2009, Nat Genet 41:724–728, and was subsequently replicated across diverse ancestral groups in the PAGE study (n=42,251)⁵⁵ PAGE study (n=42,251)
Carty et al. 2013, Hum Reprod 28:1695–1706. Notably, rs9393800-A also associates with later age at menarche (+0.172 years, p=1×10⁻⁸) in a large Japanese GWAS of 67,029 women (Horikoshi et al. 2018, Nat Commun)⁶⁶ (Horikoshi et al. 2018, Nat Commun), suggesting this locus influences the timing of both endpoints of the female reproductive lifespan through shared meiotic mechanisms.

Practical Actions

The per-allele effect of rs9393800 is approximately 0.17 years — modest at the individual level, but it accumulates with other variants at the same locus and across the broader menopause-timing polygenic architecture. For women who carry the G allele (particularly GG homozygotes), the most informative action is measurement of anti-Müllerian hormone (AMH), which provides a direct, current window into follicular reserve independent of age and before any change in cycle regularity.

Coenzyme Q10 in the ubiquinol form has the strongest evidence for supporting mitochondrial function in aging oocytes, where ATP availability intersects with the centromere-pairing process SYCP2L governs. For women with the GG genotype who are planning delayed parenthood, a fertility consultation before age 33 is warranted to review reserve trajectory.

Interactions

rs9393800 is one of at least three independently-associated variants at the 6p24.2/SYCP2L locus on chromosome 6. The other two are rs9348724 (~2 kb upstream, regulatory) and rs2153157 (intronic splice-efficiency variant). The three signals are not fully correlated, meaning a woman can carry the risk allele at all three, two, or just one, with presumably additive effects on SYCP2L expression. Women carrying the G allele at rs9393800 alongside the risk alleles at rs9348724 (C allele absent) and rs2153157 (G allele) face a compound reduction in SYCP2L availability in their oocytes. The quantitative combined effect has not been directly measured, but the additive model would predict earlier menopause timing proportional to the number of unfavourable alleles carried across all three loci.