FSHB rs1050502: Understanding Genetic Links to FSH Levels
The rs1050502 variant is a single nucleotide polymorphism located near the FSHB gene, which encodes a critical subunit of follicle-stimulating hormone. Research suggests this variant may influence basal hormone levels, potentially impacting menstrual cycle length and reproductive traits.
What each genotype means
Typical FSH baseline levels
Individuals with the CC genotype carry two copies of the standard allele near the FSHB gene. Research indicates this genotype is associated with baseline follicle-stimulating hormone levels, average menstrual cycle length, and typical population rates of spontaneous dizygotic twinning. These associations represent general statistical trends across studied cohorts and do not determine reproductive outcomes on their own.
Carried by approximately 70% to 75% of individuals of European ancestry and is the most common genotype globally.
Slightly altered FSH profile
Carriers of the CT genotype have one copy of the minor T allele associated with modestly reduced FSHB promoter activity. Published studies observe subtle statistical shifts in circulating FSH concentrations and slight variations in menstrual cycle characteristics or twinning probability compared to common homozygotes. Because evidence is limited and reproductive hormones fluctuate widely, this profile represents a minor genetic contribution rather than a clinical diagnosis.
Found in approximately 25% to 28% of people of European descent, with varying prevalence in other populations.
Lower baseline FSH propensity
Carrying two copies of the T allele is associated with lower average FSHB transcriptional activity and lower baseline circulating FSH levels in research cohorts. In reproductive studies, homozygous minor carriers show modest statistical tendencies toward altered menstrual cycle timing and reduced likelihood of multiple ovulation. These findings reflect small population-level associations and should be interpreted with caution given the limited strength of individual variant effects.
Relatively uncommon, occurring in roughly 2% to 3% of individuals of European ancestry.
What is rs1050502?
The rs1050502 variant is a specific change in the DNA sequence located in the regulatory region near the FSHB gene. In genetics, a single nucleotide polymorphism (SNP) like rs1050502 represents a variation at a single position in the genome. This particular variant is situated in a region that helps control how the FSHB gene is expressed. Because it sits in a promoter-adjacent area, researchers investigate whether it alters the efficiency with which the body produces the beta-subunit of follicle-stimulating hormone (FSH). While the human genome is remarkably similar between individuals, these small variations can lead to subtle differences in biological processes. Scientists track these markers to understand how genetic architecture contributes to the natural diversity observed in human reproductive physiology.
The Role of the FSHB Gene
The FSHB gene provides the instructions for creating the beta-subunit of follicle-stimulating hormone. FSH is a vital hormone produced by the pituitary gland that plays a central role in human reproduction. In women, it is essential for the maturation of ovarian follicles and the regulation of the menstrual cycle. In men, it is necessary for the production of sperm. Because the FSHB gene is so critical for these processes, its expression is tightly regulated. Mutations that completely disable this gene are rare and are associated with significant fertility challenges. However, common variants like rs1050502 are thought to have much more subtle effects, potentially modulating the baseline levels of FSH circulating in the blood rather than causing a complete loss of function.
Research and Evidence Strength
Current research into rs1050502 has identified statistical associations between this variant and various reproductive traits, including basal FSH levels and the duration of the menstrual cycle. Some studies have suggested that specific alleles may be linked to differences in how the body regulates hormone production, which in turn could influence twinning propensity or the timing of ovulation. However, it is important to note that the evidence strength for these associations is currently considered limited. Many of these findings come from genome-wide association studies (GWAS) that identify correlations rather than direct causation. Because reproductive health is a complex trait influenced by many genes and environmental factors, the effect size of any single SNP is typically small. Further research is required to fully understand the biological mechanisms and to determine how consistently these associations hold across different populations and clinical contexts.
Population Frequency
The frequency of the rs1050502 variant varies across different ancestral groups. According to data from the Genome Aggregation Database (gnomAD), the minor allele frequency is approximately 0.16 in European populations. This means that a significant portion of the population carries at least one copy of the less common allele. Because frequency can differ substantially based on geography and ancestry, researchers must account for these differences when conducting genetic studies. Understanding the distribution of this variant helps scientists determine whether observed associations are consistent globally or if they are specific to certain genetic backgrounds. As more diverse genomic data becomes available, our understanding of how common this variant is across the global population will continue to improve.
Interpreting Your Genetic Information
Genetic information regarding variants like rs1050502 is intended for educational purposes and should not be used for medical diagnosis or to predict individual reproductive outcomes. While research has identified statistical links between this variant and hormone levels, these associations are based on population-level data and do not necessarily apply to any single individual. Many factors, including age, lifestyle, and other genetic markers, play a much larger role in determining reproductive health than any single SNP. If you have concerns about your fertility, hormone levels, or menstrual health, it is essential to consult with a qualified healthcare provider or a reproductive endocrinologist. They can provide personalized testing and clinical guidance based on your specific medical history, which is far more informative than looking at a single genetic variant in isolation.
How common is this variant?
The minor allele frequency for rs1050502 is approximately 0.16 in European populations, though frequencies can vary across different global ancestries.
Frequently asked questions
Does rs1050502 mean I am infertile?
No. This variant is associated with subtle differences in hormone levels at a population level and is not a diagnostic marker for infertility. Individual fertility is influenced by a wide range of complex biological and environmental factors.
Can I use this SNP to predict my menstrual cycle length?
While some research has found statistical associations between this variant and menstrual cycle duration, it cannot be used to predict your personal cycle length. Many factors, including stress, nutrition, and other genetic variants, influence cycle regularity.
Should I get my FSH levels tested because of this variant?
You should only pursue medical testing if recommended by your doctor based on your personal health history. Genetic variants like this one do not provide enough information to warrant clinical testing on their own.
Is this variant linked to any diseases?
The evidence for rs1050502 is primarily focused on normal physiological variation in hormone levels. It is not currently established as a causative factor for specific reproductive diseases.
Sources & further reading
Educational information only, last refreshed 10/12/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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This missense variant in the FSHB gene is associated with spermatogenic impairment and abnormal sperm counts.
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.
Located in the promoter of FSHB (c.-211G>T), this variant downregulates follicle-stimulating hormone transcription and is strongly associated with male infertility traits (oligozoospermia) and altered female reproductive lifespan.