FCER1A rs2251746: Regulation of IgE and Allergic Response
The rs2251746 variant is a single-nucleotide polymorphism located in the promoter region of the FCER1A gene on chromosome 1. It modulates the cellular expression of the alpha subunit of the high-affinity IgE receptor (FcεRIα) and is strongly associated with circulating total serum immunoglobulin E (IgE) concentrations. Research indicates that this variant plays a significant role in baseline atopic predisposition and immune receptor density on basophils and mast cells.
What each genotype means
Lowest IgE levels
Individuals with this genotype are statistically associated with the lowest levels of serum IgE. Research suggests this variant influences the expression of the high-affinity IgE receptor on immune cells, which may correlate with lower IgE-mediated allergic responses.
This genotype is common in many populations, though exact frequencies vary by ancestry.
Intermediate IgE levels
Carriers of this genotype typically show intermediate serum IgE levels compared to those with the C/C or T/T genotypes. This reflects an allele-dose effect where the presence of the C allele is associated with a reduction in total IgE levels.
This heterozygous genotype is frequently observed across diverse populations.
Highest IgE levels
This genotype is associated with the highest levels of serum IgE among the three variants. The T allele is considered a genetic risk factor for elevated IgE, which is a key mediator in allergic sensitization and certain immune responses.
This genotype is less common than the C-containing genotypes in many European ancestry groups.
Genomic Location and Variant Characteristics
The single-nucleotide polymorphism rs2251746 is situated in the 5-prime proximal promoter regulatory region of the FCER1A gene on human chromosome 1q23. At this genomic position, the primary alleles observed in human populations are cytosine (C) and thymine (T). Functional studies indicate that rs2251746 alters local DNA binding affinity for the haematopoietic transcription factor GATA-1. This regulatory shift directly influences transcriptional activity and downstream messenger RNA output, determining how efficiently the FCER1A locus is transcribed in circulating immune cells. Because rs2251746 is located in a high-linkage disequilibrium block, it frequently co-segregates with neighboring immune-regulatory polymorphisms in the 1q23 locus, including rs2427837.
Biological Role of the FCER1A Gene
The FCER1A gene encodes the alpha subunit of the high-affinity immunoglobulin E receptor, designated FcεRIα. This membrane-spanning protein provides the essential extracellular binding domain for circulating IgE antibodies on key effector cells of the innate and adaptive immune systems, including mast cells, basophils, monocytes, and plasmacytoid dendritic cells. When multivalent allergens cross-link cell-bound IgE molecules attached to FcεRIα, it triggers rapid intracellular degranulation and the release of inflammatory mediators like histamine, leukotrienes, and cytokines. Consequently, variations in receptor density on cell surfaces influence both cellular sensitivity to allergen exposure and the rate of turnover and clearance of serum IgE.
Evidence for Association with Serum IgE and Allergy Traits
Genome-wide association studies (GWAS) have repeatedly identified rs2251746 and its proxy markers as prominent quantitative trait loci for total serum IgE levels. Large-scale cohort investigations, including replication in thousands of individuals from European population studies like KORA and the Framingham Heart Study, have demonstrated genome-wide significant associations (p-values surpassing 10^-20). In European-ancestry cohorts, carrying the minor C allele is linked with differential IgE levels and modified cell-surface expression of the receptor on basophils compared to the major T allele. While correlations with downstream clinical phenotypes like atopic dermatitis, asthma, and chronic urticaria have been explored in European and East Asian cohorts, findings for discrete disease endpoints remain moderate and show variable effect sizes.
Population Diversity and Linkage Differences
Allele frequencies and linkage architectures for rs2251746 exhibit measurable variation across worldwide ancestries. In populations of European descent, the minor allele frequency (MAF) of the C allele hovers around 0.36, representing a common polymorphic state. However, allele distributions and haplotype structures differ in other ancestral groups. For example, East Asian studies note that linkage patterns between rs2251746 and neighboring promoter markers, such as rs2427827 or rs2427837, differ from those observed in European cohorts. Because linkage disequilibrium varies across ancestral backgrounds, the predictive ability of rs2251746 can differ by population, emphasizing that genetic background strongly shapes how individual loci manifest in quantitative immune traits.
Interpreting Results in Clinical Context
It is essential to understand that rs2251746 is an observational trait marker, not a diagnostic test for allergic diseases or immune dysfunction. Total serum IgE levels in the body are polygenic and heavily influenced by non-genetic factors, such as environmental allergens, childhood microbial exposures, and parasitic encounters. Having a particular genotype at rs2251746 does not guarantee that an individual will develop asthma, eczema, or severe allergies, nor does it preclude atopic disease. Genetic results should never be used to initiate, stop, or adjust prescription allergy therapies or biologic treatments. Any questions regarding allergy management or immune health should be discussed directly with a qualified physician or allergist.
How common is this variant?
The minor allele (C) has a frequency of approximately 0.36 across European ancestry populations, with intermediate-to-high frequencies also observed in several global cohorts.
Frequently asked questions
Does having the rs2251746 C allele mean I will never get allergies?
No. While the C allele is associated with lower average total serum IgE concentrations in epidemiological studies, allergic disease is multifactorial. Environmental exposures and many other genetic variants contribute significantly to your overall allergy risk.
Can rs2251746 diagnose asthma or eczema?
No. rs2251746 is a quantitative trait locus linked to biological markers such as IgE levels and receptor expression, not a direct diagnostic marker for clinical disease. Diagnosing conditions like asthma or atopic eczema requires clinical evaluation and testing by a medical doctor.
What is the relationship between FCER1A and IgE?
FCER1A produces the alpha chain of the high-affinity IgE receptor, which sits on the surface of immune cells like mast cells and basophils. This chain binds directly to IgE molecules, enabling the immune system to sense allergens and initiate an inflammatory response.
Should I alter my allergy medications based on my rs2251746 genotype?
No, you should never alter your medications or dosages based on a direct-to-consumer genetic test result. Any adjustments to allergy medications or biologic treatments should only be made under the guidance of a prescribing healthcare provider.
Sources & further reading
Educational information only, last refreshed 9/5/2026. Not medical advice — these associations describe population statistics, not individual predictions.
Curious what your genotype is for rs2251746?
Upload a raw DNA file from 23andMe, AncestryDNA, MyHeritage, or FamilyTreeDNA and see this variant — plus thousands more — interpreted in your full report.
Get my report — $29Related variants in FCER1A
Variant in the high-affinity IgE receptor alpha subunit associated with total serum IgE concentrations and allergic sensitization.
Promoter-proximal variant regulating FCER1A transcriptional responsiveness during high-affinity IgE crosslinking on mast cells and basophils.
Regulatory variant in the high-affinity IgE receptor gene FCER1A modulating circulating total IgE concentrations and allergic manifestations.
Variant in the high-affinity IgE receptor alpha subunit locus influencing IgE receptor transcription and susceptibility to atopic allergic sensitization.
Variant in the high-affinity IgE receptor alpha chain gene strongly associated with regulation of total serum IgE levels and allergic sensitization risk.