TSLP rs4795405: What Your Genotype Means
The rs4795405 variant is a single-nucleotide polymorphism located upstream of the TSLP gene on chromosome 5. Research suggests it acts as a regulatory variant that may alter thymic stromal lymphopoietin expression, modestly influencing eosinophilic immune responses, food allergies, and related atopic traits. However, overall clinical evidence remains limited, and carrying a risk allele is neither diagnostic of an allergic disorder nor a predictor of disease severity.
What each genotype means
Typical inflammatory risk profile
You carry two copies of the common C allele upstream of the TSLP gene. Research associates this baseline genotype with typical levels of thymic stromal lymphopoietin expression and standard population-level risks for allergic inflammation. Because this variant acts as an expression modifier rather than a direct diagnostic marker, overall allergic susceptibility depends heavily on environmental triggers and broader genetic context.
Carried by approximately 30% to 35% of individuals of European ancestry and roughly 80% of individuals of East Asian descent.
Moderately altered allergic risk
You carry one copy of the T allele linked to altered promoter activity and expression of TSLP. Population-level studies indicate a modest statistical association with variations in mucosal eosinophilic inflammation, atopic reactions, and food allergies. The clinical evidence for this variant remains limited, and carrying this genotype alone does not diagnose any allergic condition.
Carried by roughly 45% to 50% of individuals of European descent and about 15% to 20% of East Asian individuals.
Altered TSLP expression profile
You carry two copies of the T allele upstream of the TSLP gene, which has been evaluated for its influence on epithelial TSLP expression. In research cohorts, this genotype has been associated with shifted susceptibility to eosinophilic immune responses, including food-related and mucosal allergic inflammation. Because current scientific evidence is limited, these associations represent statistical trends in specific populations rather than a definitive medical outcome.
Carried by approximately 15% to 20% of individuals of European descent and only 1% to 2% of East Asian individuals.
Genomic Location and Variant Characteristics
The single-nucleotide polymorphism rs4795405 is situated on chromosome 5 at the 5q22 locus, positioned in the upstream regulatory region of the TSLP (thymic stromal lymphopoietin) gene. As a non-coding upstream variant, it does not directly alter the amino acid sequence of the encoded cytokine. Instead, variants within this promoter and upstream regulatory block are evaluated for their potential to alter transcriptional activity, promoter binding affinity, or regional chromatin accessibility. In genetic databases such as dbSNP, rs4795405 represents a single base-pair substitution where an alternate allele may replace the reference nucleotide. Because of its genomic position, researchers frequently study this variant in linkage disequilibrium with other common 5q22 allergic disease loci to determine how collective regulatory variation modifies cytokine output.
Biological Role of Thymic Stromal Lymphopoietin (TSLP)
The TSLP gene encodes thymic stromal lymphopoietin, an epithelial-derived cytokine that plays an essential role in initiating and regulating mucosal and skin immune responses. Expressed predominantly by barrier epithelial cells in the airways, skin, and gastrointestinal tract, TSLP signals through a heterodimeric receptor complex consisting of the TSLP receptor (TSLPR) and interleukin-7 receptor alpha (IL-7Rα). When barrier surfaces encounter environmental triggers—such as allergens, pathogens, or physical damage—TSLP release activates myeloid dendritic cells. These activated dendritic cells subsequently promote the differentiation of naive helper T cells into T helper type 2 (Th2) cells. By driving the cascade of Th2 cytokines (such as IL-4, IL-5, and IL-13), TSLP facilitates eosinophil recruitment, immunoglobulin E (IgE) production, and allergic inflammation across several organ systems.
Research Associations and Evidence Strength
Genome-wide association studies (GWAS) and candidate gene analyses have repeatedly implicated the 5q22 region containing TSLP in susceptibility to allergic diseases, including eosinophilic esophagitis, allergic rhinitis, asthma, and food allergy. For rs4795405 specifically, current research has observed an association between the alternate allele and altered TSLP transcriptional expression, correlating with heightened susceptibility to eosinophilic mucosal inflammation and food-induced allergic reactions. However, the overall clinical evidence strength for rs4795405 remains limited. The effect sizes reported in population studies are modest, and functional validation separating the distinct impact of rs4795405 from neighboring variants in strong linkage disequilibrium is ongoing. Consequently, while the broader biological pathway is firmly established, this individual SNP explains only a small fraction of overall allergic disease risk.
Population Distribution and Genetic Context
Allele frequencies for rs4795405 vary considerably among global ancestral groups. According to population genetics catalogs, the minor allele frequency is relatively common in European-ancestry populations, where it reaches approximately 0.42. In contrast, the variant is substantially less frequent in East Asian populations, with a minor allele frequency documented near 0.10. These pronounced differences highlight the importance of ancestral context when interpreting epidemiological and genetic association findings. Because a risk allele that is common in one population may be infrequent in another, risk estimates generated in European cohorts cannot be uniformly generalized to individuals of different backgrounds without ancestry-matched validation.
Interpreting Results and Clinical Perspective
Discovering your rs4795405 genotype provides educational insight into your baseline genetic profile, but it cannot be used to diagnose any health condition. Allergic disorders, food intolerances, and eosinophilic inflammatory diseases are complex, multifactorial traits driven by dozens of genetic loci acting together with environmental exposures, microbiome factors, and childhood immune priming. Carrying an associated allele does not guarantee you will develop allergic inflammation, just as having a typical genotype does not prevent it. Consumers should not initiate dietary exclusions, alter medications, or seek medical treatments based on this single variant alone. Any concerns regarding potential food allergies or inflammatory symptoms should always be evaluated by a qualified allergist or primary care physician using validated diagnostic tools.
How common is this variant?
The minor allele frequency for rs4795405 is approximately 0.42 in populations of European ancestry, whereas it is considerably lower at approximately 0.10 in East Asian populations.
Frequently asked questions
Can rs4795405 tell me if I have a food allergy?
No, this genetic variant cannot diagnose a food allergy. It is only statistically associated with a modest change in susceptibility across large population studies. True food allergies must be evaluated clinically using medical histories, skin prick tests, or specific IgE testing under medical supervision.
What is the relationship between TSLP and eosinophils?
TSLP is a cytokine released by epithelial barriers that activates dendritic cells to trigger a Th2 immune response. This downstream pathway stimulates the release of cytokines like IL-5, which promote the production, activation, and survival of eosinophils in inflamed tissues.
Does having the risk genotype mean I need to avoid certain foods?
No, you should never make dietary changes or eliminate food groups solely based on a genetic variant. Genetic testing for rs4795405 does not identify specific food triggers or indicate active disease.
Why does the frequency of rs4795405 differ between populations?
Allele frequencies naturally shift across global populations due to historical human migrations, genetic drift, and regional selective pressures. As a result, the variant is common in European lineages (~42%) but much less frequent in East Asian groups (~10%).
Sources & further reading
Educational information only, last refreshed 9/12/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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A promoter variant regulating thymic stromal lymphopoietin expression, thereby controlling dendritic cell priming and eosinophilic allergic responses.
Upstream variant of thymic stromal lymphopoietin linked to elevated eosinophil activation and susceptibility to allergic disease.
An upstream promoter variant that alters thymic stromal lymphopoietin expression, mediating susceptibility to allergic rhinitis and childhood asthma.
A well-characterized intergenic polymorphism upstream of TSLP conferring increased risk of eczema-associated food allergy and allergic eosinophilic airway disease.
Functional TSLP locus variant associated with circulating TSLP levels and predisposition to eosinophilic inflammation and asthma.
Intergenic/promoter region SNP upstream of TSLP that strongly associates with eosinophilic esophagitis, asthma, atopic dermatitis, and allergic sensitization phenotypes.