Test code 2817

Among the top 5 causes of serious food allergic reactions.1 Determine which of these proteins your patient has high levels of IgE to:

Cor a1

LOWER RISK of systemic reaction primarily associated with local reactions2

  • Heat and digestion labile3
  • Cross-reactive with pollens (e.g., birch)4,5

Cor a8

VARIABLE RISK associated with local and systemic reactions including anaphylaxis2,6,7

  • Heat and digestion stabile8
  • Indicates cross-reactivity, often from a primary peach sensitization8

Cor a9, Cor a14

HIGHER RISK of systemic reaction including anaphylaxis2,4,9,10

  • Heat and digestion stabile11
  • Sensitization to these can appear early in life and indicates a primary hazelnut allergy4


Risk assessment and test interpretations

If antibodies are + for Cor a14 and/or Cor a9

  • Associated with systemic reactions in hazelnut-sensitized patients2,4,9,10
  • Test for sensitization to peanuts and other tree nuts (e.g., walnuts and Brazil nuts), as crossreactivity may occur11,12

If also positive for Cor a8, avoid raw as well as roasted/heated hazelnuts8


If antibodies are + for Cor a8

  • Both local oral symptoms and systemic reactions may occur2,7

If also + for Cor a14 or Cor a9, avoid raw as well as roasted/heated hazelnuts8


If antibodies are + for Cor a1

  • Typically associated with local reactions although systemic reactions to raw hazelnuts may occur in some cases, especially in adults2
  • Often tolerate roasted or heated hazelnuts8

As in all diagnostic testing, a diagnosis must be made by the physician based on test results, individual patient history, the physician’s knowledge of the patient, and the physician’s clinical judgement.


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Download the Hazelnut Allergen Component Testing brochure.


1. Flinterman AE, et al. Hazelnut allergy: from pollen-associated mild allergy to severe anaphylactic reactions. Curr Opin Allergy Clin Immunol. 2008 Jun; 8(3): 261-265.

2. De Knop KJ, et al. Age-related sensitization profiles for hazelnut (Corylus avellana) in a birch-endemic region. Pediatr Allergy Immunol. 2011 Feb; 22(1Pt 2): e139–49.

3. Hansen KS, et al. Roasted hazelnuts-allergenic activity evaluated by double-blind, placebo-controlled food challenge. Allergy. 2003 Feb; 58(2): 132-138.

4. Masthoff L, et al. Sensitization to Cor a 9 and Cor a 14 is highly specific for a hazelnut allergy in Dutch children and adults. J Allergy Clin Immunol. 2013 Aug; 132(2):393-9.

5. Pastorello EA, et al. Identification of hazelnut major allergens in sensitive patients with positive double-blind, placebo-controlled food challenge results. J Allergy Clin Immunol. 2002; 109(3): 563-570.

6. Lauer I, et al. The non-specific lipid transfer protein, Ara h 9, is an important allergen in peanut. Clinical & Experimental Allergy. 39: 1427–1437.

7. Schocker F, et al. Recombinant lipid transfer protein Cor a 8 from hazelnut: A new tool for in vitro diagnosis of potentially severe hazelnut allergy. J Allergy Clin Immunol. 2004;113:141-7.

8. Masthoff L, et al. A systematic review of the effect of thermal processing on the allergenicity of tree nuts. Allergy. 2013; 68: 983–993.

9. Hansen KS, et al. Component-resolved in vitro diagnosis of hazelnut allergy in Europe. J Allergy Clin Immunol. 2009 Apr 1; 123(5): 1134-1141.

10. Garino C, et al. Isolation, cloning, and characterization of the 2S albumin: A new allergen from hazelnut. Mol Nutr Food Res. 2010; 54: 1257–1265.

11. Asero R, et al. Walnut-induced anaphylaxis with cross-reactivity to hazelnut and Brazil nut. J Allergy Clin Immunol. 2004 Feb; 113(2): 358-360.

12. Verweij M, et al. Young infants with atopic dermatitis can display sensitization to Cor a 9, an 11S legumin-like seed-storage protein from hazelnut (Corylus avellana). Pediatric Allergy Immnol. 2011; 22: 196-201.