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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. - PowerPoint PPT Presentation
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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 practicePatient
At 4 yearsAnamnesis
SPT to soy SPT to birch
DiagnosisAdvice
Anna
Eczema, Wheeze
+2 +2
Soy and birch allergyAvoid soy
Oliver
Eczema, Wheeze
+2 +2
Soy and birch allergyAvoid soy
Using components in clinical practice
Improved diagnoses and altered advice
Patient
At 4 yearsAnamnesis
SPT to soySPT to birchAt 8 years sIgE to soyGly m 4Gly m 5Gly m 6sIgE to birch
Diagnosis
Advice
Anna
Eczema, Wheeze Milk allergy outgrow+2 +2
0.8 kUA/l
15< 0.1< 0.158
Pollen-associated soy allergy Birch pollen allergy
No need for total avoidance Avoid large amounts of unprocessed soy
Oliver
Eczema, WheezeMilk allergy outgrow+2+2
24 kUA/l
2.516.2 6.7 20
Genuine soy allergyBirch pollen allergy
Strict soy avoidance
Soy components
Soy components
Latin name: Gly m - Glycine max
Gly m 4
Gly m 5Gly m 6
Soy components
Risk assessment of soy components
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
Peanut (f13) 72.1
Ara h 1 22.4Ara h 2 23.1
Ara h 3 13.4Ara h 8 3.7
Ara h 9 <0.1
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 5 1.4Gly m 6 2.2
In conclusion
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
Extra slides