Soy Allergy. Important protein source Sensitization frequency varies largely Prevalence of soy allergy 0.1-0.4% Symptoms cuteaneous or gastrointestinal respiratory and systemic reactions may occur Commonly used as additive in foods. Different types of soy allergy.
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Soy Allergy • Important protein source • Sensitization frequency varies largely • Prevalence of soy allergy 0.1-0.4% • Symptoms • cuteaneous or gastrointestinal • respiratory and systemic reactions may occur • Commonly used as additive in foods
Different types of soy allergy • Genuine soy food allergy • Mostly in small children • Often resolves in childhood • Soy allergy due to cross-reactivity • Mainly in adults • In birch-related tree pollen allergic patients • In legume allergic patients • Occupational allergy
Doctor's challenges • What kind of soy allergy is it? • Is it a genuine soy allergy or are the symptoms caused by cross-reactivity? • Is there a risk for systemic reactions? • Is strict avoidance necessary? • What dietary advice should be given? Genuine or cross-reactive soy allergy?
Common clinical practice Patient At 4 years Anamnesis SPT to soy SPT to birch Diagnosis Advice Anna Eczema, Wheeze +2 +2 Soy and birch allergy Avoid soy Oliver Eczema, Wheeze +2 +2 Soy and birch allergy Avoid soy
Using components in clinical practice Patient At 4 years Anamnesis SPT to soySPT to birch At 8 years sIgE to soy Gly m 4 Gly m 5 Gly m 6 sIgE to birch Diagnosis Advice Anna Eczema, Wheeze Milk allergy outgrow +2 +2 0.8 kUA/l 15 < 0.1 < 0.1 58 Pollen-associated soy allergy Birch pollen allergy No need for total avoidance Avoid large amounts of unprocessed soy Oliver Eczema, Wheeze Milk allergy outgrow +2+2 24 kUA/l 2.5 16.2 6.7 20 Genuine soy allergyBirch pollen allergy Strict soy avoidance Improved diagnoses and altered advice
Soy components Gly m 4 Gly m 6 Gly m 5 Latin name: Gly m - Glycine max
Gly m 4 • A cross-reactivity marker, associated with allergy to birch and birch-related tree pollens • A PR-10 protein, homologous to birch component Bet v 1 • Labile protein - mainly causing local symptoms, e.g. OAS, but systemic reactions may occur
Cross reactivity - birch and soy Sensitization to soy Gly m 4 likely induced via sensitization to birch
Gly m 5 and Gly m 6 • Are specific marker allergens for soy allergy • Are storage proteins- proteins expressed in legumes, seeds and nuts • Stable and heat resistant proteins that may cause systemic reactions
Peanut associated soy allergy Boy 15 years old with confirmed peanut and birch allergies. Upon having a Japanese lunch he gets mouth itch. Soybean (f14) 1.5 Gly m 4 1.9 Gly m 51.4 Gly m 6 2.2 Peanut (f13) 72.1 Ara h 1 22.4 Ara h 2 23.1 Ara h 3 13.4 Ara h 8 3.7 Ara h 9 <0.1
What does Molecular Allergology add? • Differentiation between genuine soy allergy and soy allergy due to cross-reactivity • Enables assessment of the risk for systemic reactions • Enables more precise dietary advice