IL1RL1 rs420459: Understanding Genetic Links to Allergic Asthma
The rs420459 variant is a single nucleotide polymorphism located within the IL1RL1 gene. It is statistically associated with altered IL-33 signaling and a heightened risk for allergic asthma and atopy.
What each genotype means
Typical IL1RL1 signaling
This genotype represents the common form of the IL1RL1 gene in many populations. Research into this variant focuses on its role in IL-33 signaling, which is a pathway involved in immune responses and inflammation. Because the evidence linking this specific variant to clinical outcomes is limited, this result should not be used to predict personal health or diagnose conditions.
This is the most common genotype in many global populations, though frequencies vary significantly by ancestry.
Altered IL-33 signaling potential
This genotype includes one copy of the variant allele associated with potential changes in IL-33/ST2 signaling. While some studies suggest that variations in this gene may influence susceptibility to allergic asthma or atopy, the clinical significance remains limited and is not definitive. Please consult with a healthcare provider if you have concerns about respiratory health or allergic conditions.
This heterozygous genotype is found in a significant portion of the population, with higher prevalence in European cohorts compared to East Asian populations.
Increased IL-33 signaling risk
This genotype carries two copies of the variant allele, which has been studied for its association with altered IL-33 signaling and potential risk for allergic asthma. The evidence for this association is considered limited, and the biological impact can vary based on other genetic and environmental factors. This information is for educational purposes and should not be used for medical decision-making.
This genotype is less common than the homozygous reference, with a frequency reflecting the minor allele distribution of approximately 0.38 in Europeans and 0.18 in East Asians.
What is rs420459?
The rs420459 variant is a specific genetic change, or single nucleotide polymorphism (SNP), located within the IL1RL1 gene. In genomics, a SNP represents a variation at a single position in the DNA sequence among individuals. The IL1RL1 gene provides instructions for creating the ST2 protein, which plays a critical role in the immune system. Because this variant sits within a region of the genome known to influence immune regulation, researchers study it to understand how subtle differences in DNA sequence might contribute to the development of inflammatory conditions. It is important to note that rs420459 is just one of many variations within this gene, and its presence does not guarantee the development of any specific health condition.
The Role of the IL1RL1 Gene
The IL1RL1 gene encodes the ST2 receptor, which is a key component of the IL-33 signaling pathway. This pathway is essential for regulating type 2 inflammation, a type of immune response often involved in allergic reactions and asthma. The ST2 protein exists in two main forms: a transmembrane receptor that helps transmit signals and a soluble form (sST2) that acts as a decoy receptor. By binding to IL-33, the soluble decoy receptor can prevent it from activating the transmembrane receptor, effectively dampening the inflammatory signal. Genetic variations in IL1RL1 can influence the production or function of these proteins, potentially altering how the body responds to environmental triggers that typically activate the IL-33 pathway.
Research and Evidence Strength
Research into rs420459 and other variants in the IL1RL1 gene has primarily focused on their statistical associations with allergic asthma and atopy. Genome-wide association studies (GWAS) have identified the IL1RL1 locus as a significant region for asthma susceptibility. However, the evidence specifically linking rs420459 to clinical outcomes is currently considered limited. While some studies suggest that variants in this gene influence sST2 levels and airway inflammation, the functional consequences of rs420459 specifically are not fully characterized. It is common in genetic research for initial associations to require further validation across diverse populations and larger cohorts to confirm their clinical relevance. Consequently, this variant is viewed as a subject of ongoing scientific investigation rather than a definitive diagnostic marker.
What You Can Do With This Information
Genetic information regarding variants like rs420459 is intended for educational purposes and should not be used for self-diagnosis or to make medical decisions. Because the link between this variant and health outcomes is complex and influenced by many other genetic and environmental factors, it cannot predict whether an individual will develop asthma or allergies. If you are concerned about respiratory health, allergic symptoms, or the management of existing conditions, it is essential to consult with a qualified healthcare professional. They can provide personalized guidance based on your clinical history and symptoms. If you are currently prescribed medications for asthma or allergies, always discuss any questions regarding your treatment or dosing with your clinician or pharmacist before making changes.
How common is this variant?
The minor allele frequency for rs420459 is approximately 0.38 in European populations and approximately 0.18 in East Asian populations.
Frequently asked questions
Does having the rs420459 variant mean I have asthma?
No. Genetic variants are statistical markers associated with a higher or lower likelihood of a condition, not a diagnosis. Many people with this variant do not have asthma, and many people with asthma do not carry this specific variant.
Can I use this SNP to predict my allergy risk?
Current evidence is too limited to use this SNP as a predictive tool for individual allergy risk. Asthma and allergies are complex conditions influenced by hundreds of genetic variants and significant environmental factors.
Should I change my asthma medication based on my genotype?
Absolutely not. You should never alter your medication or dosing based on genetic test results without consulting your doctor. Always speak with your clinician or pharmacist regarding your treatment plan.
Where can I find more information on IL1RL1?
You can explore resources like the GWAS Catalog or the National Center for Biotechnology Information (NCBI) Gene database. These platforms provide peer-reviewed research and summaries of genetic associations.
Sources & further reading
Educational information only, last refreshed 9/26/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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An intergenic regulatory variant upstream of IL1RL1 that influences circulating soluble ST2 levels and severity of allergic rhinitis.
This variant in the IL1RL1/IL18R1 locus influences ST2 receptor expression and modifies individual susceptibility to allergic sensitization and asthma.
Intronic regulatory variant in the IL1RL1/IL18R1 cluster modulating ST2 receptor expression and inflammatory disease risk.
A regulatory variant within the IL1RL1 (ST2) gene locus associated with allergic rhinitis, eosinophil count regulation, and atopic asthma susceptibility.
Intronic regulatory SNP in IL1RL1/ST2 associated with sST2 expression levels and susceptibility to allergic sensitization and asthma.
Variant in IL1RL1 (ST2) associated with allergic inflammation and cytokine production.