Last reviewed: May 12, 2026 Last updated: May 12, 2026

Written by: Jay Hastings , CEO of PlexusDx

Jay Hastings is the CEO of PlexusDx, a precision health company focused on genetic testing, blood biomarker insights, and personalized wellness recommendations. He has more than 20 years of experience across healthcare innovation, genomics, laboratory operations, healthcare investing, and strategic finance. His work has included scaling healthcare startups, leading CLIA lab integrations, and helping expand consumer access to precision health tools.

Medically reviewed by: Jayden Lee, PharmD, EMBA

Jayden Lee, PharmD, EMBA, is the PlexusDx Medical Science Liaison with a PharmD and MBA specializing in pharmacogenomics and clinical product development, with a proven ability to bridge the gap between genomic research and practical patient outcomes. Dr. Lee has more than 10 years of professional experience in clinical pharmacy, academia, and research.

Understanding Birch Pollen Sensitivity and Your CHI3L1 Genotype

Birch pollen allergy is a common seasonal condition that can cause itchy eyes, runny nose, sneezing, and breathing difficulties. These symptoms happen because the immune system reacts to harmless proteins in birch pollen as if they were a threat. One gene that can influence how your body responds to birch pollen is CHI3L1. This gene encodes chitinase-3-like protein 1, a protein that helps regulate immune system activity. Variations in CHI3L1 can change how strongly your immune system reacts to pollen and may affect your tendency to experience allergy symptoms.

How to Read Your Result

This report focuses on a single genetic variant called rs880633 in the CHI3L1 gene. The possible genotypes are:

  • GG: two copies of the effect allele
  • CG: one copy of the effect allele
  • CC: two copies of the non-effect allele

Important note: genetics is only one factor. Having a variant associated with increased sensitivity does not guarantee you will develop an allergy. Environmental exposures, other genes, your immune history, and lifestyle all matter. PlexusDx does not provide medical advice. Always consult your healthcare provider about symptoms, testing, and treatment options.

Genetic Interpretation

2 effect alleles (GG)

If you have the GG genotype for rs880633, you carry two copies of the effect allele. This genetic profile indicates greater immune sensitivity to birch pollen and may make you more prone to allergy symptoms. The CHI3L1 gene produces chitinase-3-like protein 1, a regulator of immune activity. The GG variant is associated with a heightened immune response when exposed to birch pollen, which can lead to symptoms such as itchy eyes, runny nose, sneezing, and respiratory discomfort during birch pollen season.

Remember this is a predisposition not a diagnosis. If you experience symptoms, discuss evaluation and management with your healthcare provider. They may recommend testing such as skin prick testing or specific IgE blood tests, and discuss treatment options including avoidance strategies, medications, and immunotherapy if appropriate.

1 effect allele (CG)

If you have the CG genotype for rs880633, you carry one copy of the effect allele. This pattern is associated with a possible moderate sensitivity to birch pollen exposure. The CHI3L1 gene produces chitinase-3-like protein 1, which helps regulate immune responses to environmental allergens. With one effect allele, your immune system may have a moderate tendency to react more noticeably when exposed to birch pollen proteins. You might experience symptoms such as itchy eyes, runny nose, occasional sneezing, or mild respiratory discomfort during pollen season.

This result indicates an increased likelihood of sensitivity but does not confirm an allergy. If symptoms occur, consult your healthcare provider to consider objective testing and to develop a personalized plan for symptom management and prevention.

0 effect alleles (CC)

If you have the CC genotype for rs880633, you carry two copies of the non-effect allele. This suggests you do not carry the G allele linked with heightened immune sensitivity to birch pollen. Your genotype indicates a standard immune response pattern when exposed to birch pollen allergens. With the CC genotype, you lack the specific genetic variant associated with increased immune reactivity to birch pollen proteins.

That said, absence of this variant does not guarantee you will never develop symptoms. Other genes and environmental factors also influence allergy development. If you experience seasonal symptoms, speak with your healthcare provider about evaluation and management options.

Practical Steps to Manage Birch Pollen Sensitivity

Whether your risk is higher, moderate, or lower based on this single genetic result, the following diet, supplements, and lifestyle strategies can help reduce inflammation and support immune balance during pollen season.

Diet Recommendations

  • Follow an anti-inflammatory eating pattern centered on whole foods. Emphasize vegetables, fruits, whole grains, legumes, nuts, seeds, and healthy fats such as olive oil.
  • Choose colorful fruits and vegetables rich in natural antioxidants and flavonoids to help modulate immune responses.
  • Include omega-3 rich foods like fatty fish, walnuts, and chia seeds which can support balanced inflammation signaling.
  • Limit processed foods, high-sugar items, and trans fats which can promote inflammation and worsen symptoms.
  • Staying hydrated helps keep mucous membranes moist and can ease nasal and throat discomfort.

Supplements to Consider

  • Quercetin: a plant flavonoid thought to stabilize mast cells and reduce histamine release. Typical supplemental doses range but check with your healthcare provider before starting.
  • Vitamin C: supports immune health and acts as an antioxidant. Adequate dietary intake or supplementation can be helpful during allergy season.
  • Probiotics: some probiotic strains can support healthy immune regulation. Discuss strain and dose with your provider.
  • Omega-3 supplements: fish oil or algal oil can support anti-inflammatory pathways if dietary intake is low.

Before starting any supplement, confirm safety, dosing, and interactions with your healthcare provider, especially if you are pregnant, breastfeeding, taking medications, or have chronic health conditions.

Lifestyle Habits

  • Monitor local pollen forecasts and limit outdoor activity when birch pollen counts are high.
  • Use HEPA filters and consider air purifiers indoors to reduce airborne allergens.
  • Keep windows closed during high pollen days and use air conditioning in both home and car when possible.
  • Shower and change clothes after spending time outdoors to remove pollen from skin and hair.
  • Practice stress reduction techniques such as regular sleep, mindfulness, gentle exercise, and breathing exercises. Stress can amplify immune responses and symptoms.
  • Speak with your healthcare provider about established allergy treatments, including antihistamines, nasal corticosteroids, or allergy immunotherapy if symptoms are persistent or severe.

When to Seek Medical Evaluation

  • If seasonal nasal or eye symptoms significantly affect daily life or sleep
  • If you experience wheezing, chest tightness, or breathing difficulty
  • If over-the-counter measures and lifestyle changes do not provide adequate relief
  • If you want definitive testing such as skin prick testing or specific IgE blood tests to confirm sensitization

PlexusDx provides educational genetic information about predispositions and tendencies. We do not provide medical advice. Always consult your healthcare provider to interpret genetic results in the context of your medical history, symptoms, and appropriate testing and treatment plans.

If this genetic variant is present in your PlexusDx results, the following tests and reports are commonly used to explore it further:

🧬 Genetic Tests:

🧪 Blood Tests:

📄 Genetic Report:

Frequently Asked Questions About Birch Pollen and CHI3L1 rs880633

What does the CHI3L1 rs880633 variant mean for birch pollen allergy sensitivity?

The CHI3L1 gene encodes chitinase-3-like protein 1, which helps regulate immune activity. The rs880633 variant may influence how strongly your immune system reacts to birch pollen proteins, affecting your likelihood of experiencing common symptoms such as itchy eyes, runny nose, sneezing, and respiratory discomfort during birch pollen season.

How do the rs880633 genotypes (GG, CG, CC) differ in birch pollen reactivity?

GG (two effect alleles) is associated with greater immune sensitivity to birch pollen and may increase your tendency to develop more noticeable allergy symptoms. CG (one effect allele) suggests possible moderate sensitivity. CC (two non-effect alleles) indicates you do not carry the effect allele linked with heightened birch pollen sensitivity, corresponding to a standard immune response pattern—though allergy symptoms can still occur due to other genes and environmental factors.

What practical steps can help manage birch pollen sensitivity based on your genetic result?

Support immune balance with an anti-inflammatory whole-food eating pattern, including omega-3 rich foods, and consider supplements such as quercetin, vitamin C, probiotics, or omega-3 if appropriate for you. During pollen season, monitor pollen forecasts, reduce outdoor exposure when counts are high, use HEPA filtration, keep windows closed, shower and change clothes after being outside, and practice stress reduction since stress can amplify immune responses. If symptoms significantly affect daily life, you have wheezing or breathing difficulty, or OTC/lifestyle steps aren’t enough, consider speaking with your healthcare provider about objective testing (like skin prick or specific IgE blood tests) and treatment options including antihistamines, nasal corticosteroids, or immunotherapy.

What tests can help me learn more about Birch Pollen and CHI3L1 rs880633?

The Food Sensitivity & Allergy Genetic Test analyzes over 240 genetic insights related to immune response, inflammation, and dietary tolerance. The Allergies and Food Sensitivities Genetic Report translates your results into personalized, actionable guidance. Your healthcare provider can also recommend targeted blood tests based on your specific pathway results and health history to complement your genetic insights with current biomarker data.

Medical and Editorial Standards

Medical review process: This article was reviewed for medical accuracy, scientific clarity, evidence alignment, and appropriate discussion of genetics, medications, supplements, biomarkers, and health-related claims.

Sources and evidence: PlexusDx educational content is developed using peer-reviewed research, clinical literature, reputable medical references, and, where applicable, public health or regulatory guidance. References are included at the end of the article when scientific, medical, or health-related claims are discussed.

Commercial transparency: PlexusDx offers genetic testing, blood biomarker testing, personalized supplement recommendations, and related precision wellness services. Product mentions are intended to help readers understand available options and should not be interpreted as medical advice.

Important disclaimer: PlexusDx educational content is for informational purposes only and should not be used as a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making decisions about medications, supplements, genetic testing, lab testing, or health-related care.