FSHB rs1799762: Reproductive Lifespan and Fertility
The rs1799762 polymorphism is a regulatory variant located in the promoter region of the FSHB gene, historically designated as c.-211G>T. This variant directly influences transcription of the beta subunit of follicle-stimulating hormone (FSH), modifying circulating gonadotropin concentrations. In genetic association studies, the minor allele has been linked to variations in male semen quality as well as subtle shifts in female reproductive lifespan and menstrual cycle dynamics.
What each genotype means
Typical FSHB promoter activity
This is the most common genotype, often considered the reference or wild-type sequence. Research indicates that individuals with this genotype typically maintain standard levels of follicle-stimulating hormone (FSH) transcription compared to those carrying the T allele.
This is the major genotype, found in the vast majority of individuals across most global populations.
Reduced FSHB promoter activity
Carrying one copy of the T allele is associated with a measurable reduction in FSHB promoter activity and lower circulating serum FSH levels. While many individuals with this genotype experience no clinical issues, it is statistically associated with subtle changes in reproductive hormone profiles.
Carried by approximately 22% of individuals in some European cohorts, though frequencies vary significantly by ancestry.
Lower FSH levels and reproductive impact
Individuals with two copies of the T allele show the most pronounced reduction in FSHB promoter activity and significantly lower serum FSH levels. Research has linked this genotype to altered reproductive traits, including decreased testicular volume and sperm counts in some men, as well as variations in reproductive lifespan in women. If you have concerns regarding fertility or reproductive health, please discuss these findings with a reproductive endocrinologist or fertility specialist.
This is a rare genotype, observed in approximately 1% of some European populations, though it may be more or less common in other ethnic groups.
Genomic Context and Molecular Mechanism
The single nucleotide polymorphism cataloged as rs1799762 (frequently studied under the proxy identifier rs10835638 in reproductive genetics) resides in the 5' regulatory promoter region of the follicle stimulating hormone subunit beta (FSHB) gene on chromosome 11p13. Specifically designated as c.-211G>T, the substitution alters a conserved regulatory element crucial for transcriptional initiation in the pituitary gland. Molecular studies indicate that the alternative T allele impairs the binding of the pituitary homeodomain transcription factor LHX3, resulting in diminished basal transcription of the FSHB mRNA. Because the production of the beta subunit is the rate-limiting step in forming dimeric, biologically active follicle-stimulating hormone, individuals carrying this substitution typically exhibit lower baseline levels of circulating FSH compared to non-carriers.
The Biological Role of Follicle-Stimulating Hormone
Follicle-stimulating hormone is an essential glycoprotein gonadotropin synthesized and secreted by gonadotroph cells in the anterior pituitary under the pulsatile stimulation of gonadotropin-releasing hormone (GnRH). In biological males, FSH targets the Sertoli cells within the seminiferous tubules of the testes, orchestrating spermatogenesis, testicular growth, and the maintenance of adequate sperm counts. In biological females, FSH acts on the granulosa cells of the ovaries to promote the recruitment, maturation, and follicular growth necessary for normal ovulation and estrogen biosynthesis. Because FSH sits at the core of the hypothalamic-pituitary-gonadal (HPG) endocrine axis, subtle lifelong reductions in its baseline production can reverberate through gametogenesis, endocrine timing, and gonad tissue maintenance in both sexes.
Clinical and Research Associations
Evidence linking the FSHB promoter variant to reproductive physiology spans both male and female cohorts, though the strength of association varies across study designs. In men, multiple clinical studies have reported an overrepresentation of the T allele in individuals with idiopathic oligozoospermia (low sperm concentration), reduced testicular volume, and lower circulating FSH levels, although some unselected population cohorts show milder modulatory effects without clinically severe semen degradation. In women, large-scale studies including the UK Biobank have correlated the FSH-lowering T allele with slightly longer menstrual cycles (roughly one day per allele), marginally later age at natural menopause, and a statistically decreased risk of endometriosis, likely mediated by lower follicular estrogen exposure. Because findings in some general-population cohorts show subtle physiological shifts rather than overt disease, the overall evidence strength for direct diagnostic causality is classified as limited to moderate.
Ancestry and Population Frequencies
The distribution of alleles at the FSHB c.-211G>T locus demonstrates marked ancestral divergence across global populations. The alternative T allele is most frequently observed in populations of European descent, exhibiting a minor allele frequency of approximately 0.15 to 0.16. In contrast, it is significantly less common in individuals of East Asian ancestry, where minor allele frequencies typically remain around 0.02. South Asian cohorts display an intermediate frequency of approximately 0.08. These pronounced differences mean that any population-level predisposition to lower baseline FSH mediated by this specific promoter variant is more prevalent in Western Eurasian groups, underscoring the necessity of interpreting genetic screening results within an individual's specific ancestral context.
Understanding Your Results: Context and Practical Guidance
Identifying an alternative allele at rs1799762 does not equate to a diagnosis of infertility, primary ovarian insufficiency, or any endocrine disorder. Human fertility and reproductive lifespans are complex, highly polygenic traits shaped by hundreds of genetic loci alongside vital lifestyle, metabolic, and environmental influences. Carrying one or two T alleles merely points to a statistical propensity for lower baseline FSH transcription. Genotype results cannot replace comprehensive clinical evaluations, such as standard semen analysis or dynamic serum reproductive hormone panels (including FSH, LH, and estradiol). If you are undergoing fertility assessments or assisted reproductive treatments, share your comprehensive history with a qualified endocrinologist, urologist, or reproductive specialist rather than altering clinical expectations based solely on a single genetic variant.
How common is this variant?
The minor T allele occurs at a frequency of approximately 15% in populations of European ancestry, about 8% in South Asian populations, and is uncommon in East Asian groups at around 2%. Consequently, homozygous TT individuals are rare outside of European-descended cohorts.
Frequently asked questions
Does having the rs1799762 T allele mean I will be infertile?
No. The presence of a T allele is a statistical risk factor for lower baseline hormone production, not a definitive cause of infertility. Many individuals carrying one or two copies of this variant have entirely normal fertility and conceive naturally without medical intervention.
How does this FSHB variant affect female menstrual cycles?
Large genetic studies show that each copy of the FSH-lowering T allele is associated with an average increase in menstrual cycle length of approximately one day. This subtle slowing of follicular development is also associated with a slightly later age at natural menopause and lower risk for endometriosis.
Can taking hormone supplements overcome this genetic variation?
Because this variant impairs the pituitary gland's natural production of FSH, medical providers sometimes evaluate gonadotropin levels during fertility treatment. Any gonadotropin therapy or hormone management must be determined and prescribed by a reproductive endocrinologist based on direct clinical lab testing.
Why is this variant also discussed as rs10835638?
In scientific literature, the promoter variant c.-211G>T is commonly referenced interchangeably under rs1799762 or the high-linkage tag rs10835638. Both denote the same regulatory change controlling FSH beta-subunit expression on chromosome 11.
Sources & further reading
Educational information only, last refreshed 9/5/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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Promoter-adjacent variant linked to FSHB expression, influencing basal follicle-stimulating hormone levels, menstrual cycle duration, and twinning propensity.
Pathogenic loss-of-function variant causing isolated follicle-stimulating hormone deficiency leading to hypogonadotropic hypogonadism.
Functional promoter variant in FSHB influencing serum FSH concentrations and reproductive lifespan.
Variant in the promoter region of FSHB associated with circulating follicle-stimulating hormone levels, age at menarche, and reproductive lifespan.
Variant in the promoter region of FSHB associated with altered follicle-stimulating hormone levels, timing of menarche, and female reproductive lifespan.
Functional variant in FSHB causing congenital isolated follicle-stimulating hormone deficiency.