Expanding Molecular Precision in Tree Nut Allergy Diagnostics

Why advanced diagnostics matter

Tree nut allergies are among the most severe IgE-mediated food allergies, contributing to anaphylaxis cases of 33%–48% in the U.S. and 16% in Europe.^{1, 2} Walnut is the most frequently implicated nut in tree nut anaphylaxis cases in the U.S.^{1, 3}, while hazelnut allergy is one of the most common tree nut allergies in Europe⁴, with sensitization rates as high as 17% in school-age children and nearly 7% in adults in birch-pollen endemic areas⁵.

Walnut and hazelnut allergies often co-exist and together with other tree nuts and peanut, account for a major share of food related anaphylaxis.^{6, 7} Some walnut and hazelnut allergic patients test negative for sensitization to major allergen components while demonstrating sensitization to whole allergens.^{8, 9}

7S globulin storage proteins are clinically important markers linked to systemic reactions, yet they are not usually available in current diagnostic allergy tests. ^{5, 12, 13} Introducing new vicilin-type allergen components into walnut and hazelnut testing helps close these gaps and provides a more complete view of sensitization patterns.

The clinical need – uncovering hidden sensitizations

7S globulins are highly stable storage proteins that withstand heat and digestion and are associated with primary sensitization and an increased risk of systemic reactions. Despite their clinical relevance, vicilin-type allergen components have not been previously available in walnut and hazelnut diagnostic panels, leaving sensitizations undetected in some patients.^{9, 10}

For some individuals, vicilins may be the only storage proteins to which they are sensitized. Without these markers, clinically allergic patients can test negative to existing walnut and hazelnut components, complicating diagnosis and risk assessment. Importantly, vicilin sensitization helps distinguish clinically significant primary food allergy from cross-reactive pollen-related sensitization (e.g., PR-10, profilins).¹¹

 Adding Cor a 11, Cor a 16, Jug r 2 and Jug r 6 helps uncover these hidden sensitizations, clarifies primary versus cross-reactive patterns, and provides a more complete molecular picture of walnut and hazelnut allergy.^{10, 11}

The evidence – what the science shows

Recent evidence demonstrates that the addition of vicilin-type allergen components significantly improves the identification of clinically relevant hazelnut and walnut allergy, particularly in patients not detected by existing storage-protein markers.

Hazelnut allergy

• Cor a 11 and Cor a 16 are associated with systemic and anaphylactic reactions, especially in children, and help to differentiate primary hazelnut sensitization from birch pollen–related oral allergy syndrome.^{8, 11, 12, 14}
• In a cohort of 106 patients, 19% showed exclusive sensitization to Cor a 11 or Cor a 16 while testing negative to other allergen components. 53% of patients negative for Cor a 14 showed sensitization to Cor a 11 and/or Cor a 16, highlighting their complementary diagnostic role. ^{10, 14}

Walnut allergy

• Jug r 2 and Jug r 6 correlate with moderate-to-severe reactions independent of pollen sensitization.^{2, 13}
• Jug r 6 is a major vicilin responsible for IgE cross-reactivity across multiple tree nuts and seeds, while Jug r 2 has been linked to confirmed anaphylaxis, even in monosensitized patients.^{13, 15, 16}
• Notably, 63% of Jug r 1–negative cases show sensitization to Jug r 2 and/or Jug r 6, demonstrating their added value in identifying high risk patients.¹⁰

Enhancing diagnostic sensitivity

When combined with established storage protein components (Jug r 1, Cor a 9, Cor a 14), the inclusion of Cor a 11, Cor a 16, Jug r 2 and Jug r 6 delivers more complete molecular coverage of walnut and hazelnut storage-protein sensitization.

These findings align with international recommendations supporting the use of component-resolved diagnostics alongside whole allergen testing in identifying clinically significant allergen sources and guiding patient management.¹⁷

Clinical implications – what it means for patient care

Broader testing with molecular allergen components together with whole allergen provides clinicians with clearer insight into a patient’s risk profile and supports safer, more informed allergy management decisions:

• Aid differentiation of primary walnut and hazelnut allergy from pollen-related cross‑reactivity, helping clinicians understand which patients are at risk for systemic reactions.
• Identify high-risk patients earlier, including those who may test negative to existing storage-protein markers and are sensitized only to vicilins.
• Guide decisions around oral food challenges by clarifying sensitization patterns upfront, reducing unnecessary challenges and improving patient safety.
• Support targeted dietary advice and evidence-based emergency preparedness, including when epinephrine prescribing or strict avoidance is appropriate.^{11, 12}

In summary, these new vicilin-type allergen components contribute to safer, personalized allergy management across the care continuum.

The expanded portfolio – advancing diagnostic precision

Thermo Fisher Scientific now offers four new vicilin-type allergen components that meaningfully extend walnut and hazelnut molecular diagnostics.

Positioning within molecular allergy diagnostics

These vicilin-type allergen components integrate seamlessly into Thermo Fisher Scientific’s established molecular diagnostic framework¹⁸, which spans multiple clinically relevant protein families.

• Profilins: ImmunoCAP profilin components (e.g., Bet v 2, Phl p 12) support the identification of pollen–food cross-reactivity associated with broad, often mild sensitization patterns.
• PR-10 proteins: ImmunoCAP PR-10 components (e.g., Jug r 3, Bet v 1, Mal d 1, Cor a 1) reveal heat-labile sensitization commonly linked to oral allergy syndrome.
• Lipid Transfer Proteins (LTPs): ImmunoCAP LTP markers (e.g., Pru p 3, Cor a 8) detect stable allergens associated with an increased risk of systemic reactions.
• Storage proteins (2S albumin, 7S globulin, 11S globulin): ImmunoCAP storage-protein components are central to assessing clinically significant food allergy risk, as these stable proteins are strongly associated with persistent and potentially severe reactions. In particular, 7S globulins (vicilins) represent a key storage-protein family in tree nuts. The addition of Cor a 11 and Cor a 16 completes hazelnut 2S and 11S storage‑protein coverage, while Jug r 2 and Jug r 6 provide comprehensive coverage of walnut vicilin storage proteins, strengthening molecular resolution for risk stratification in hazelnut and walnut allergy.

Conclusion

Tree nut allergy diagnosis requires high precision, quantification, sensitivity and specificity. With the introduction of Jug r 2, Jug r 6, Cor a 11, and Cor a 16, Thermo Fisher Scientific enhances the storage‑protein profile for walnut and hazelnut and closes important diagnostic gaps. These advancements enhance confidence in clinical decision-making and support safer, more personalized allergy management across specialist allergist practices and diagnostic laboratory settings.