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Egg Allergy. Important food allergy in children Starts early in life Often resolved by school age Symptoms: atopic dermatitis, urticaria, asthma, anaphylaxis Sensitization may predict atopic disease later in life Prevalence: 1-2% Boiled/heated egg may be tolerated . Doctor's challenges.
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Egg Allergy • Important food allergy in children • Starts early in life • Often resolved by school age • Symptoms: • atopic dermatitis, urticaria, asthma, anaphylaxis • Sensitization may predict atopic disease later in life • Prevalence: 1-2% • Boiled/heated egg may be tolerated
Doctor's challenges • Is there a risk for severe reactions? • Could the patient tolerate cooked egg? • Is the allergy likely to be persistent? • How should the patient best be managed? • Who needs strict avoidance? • Who needs emergency medication?
Common clinical practice Patient Previous At 7 months Anamnesis At 2 years Anamnesis SPT to egg Diagnosis Advice At 5 years sIgE to egg Food challenge Diagnosis Elin, 5 years Eczema Urticaria, asthma +5 Egg allergy Avoid egg 25 kUA/l No symptoms Tolerant to egg Nour, 5 years Eczema Urticaria, asthma +4 Egg allergy Avoid egg 20 kUA/l Urticaria, cough, rhinitis Egg allergy
Main egg allergen components Gal d 2 Gal d 3 • Ovomucoid – Gal d 1 • Ovalbumin – Gal d 2 • Ovotransferrin – Gal d 3 • Lysozyme – Gal d 4 Gal d 1 Gal d 4 Latin name: Gal d – Gallus domesticus
Ovomucoid - Gal d 1 • The dominant egg white component • 11 % of egg white content • Highly allergenic • Stable to heat and enzymatic digestion Gal d 1
Ovomucoid and tolerance • Boiled egg may be tolerated if Ovomucoid-IgE levels are low • Persistent egg allergy is seen in patients with high Ovomucoid-IgE levels The stability of Ovomucoid reflects the clinical picture
Using components in clinical practice Patient Previous At 7 months Anamnesis At 2 years Anamnesis SPT to egg sIgE to egg sIgE to Ovomucoid Diagnosis Advice Elin, 5 years Eczema Urticaria, asthma +5 25 kUA/l 0.4 kUA/l Tolerance likely Low risk for reactions Try cooked egg Nour, 5 years Eczema Urticaria, asthma +4 20 kUA/l 12 kUA/l Egg allergy Avoid egg Improved diagnoses and altered advice
What does Molecular Allergology add? Sensitization to Ovomucoid indicates: • Risk for reaction to all forms of egg • Persistent egg allergy • Risk for systemic reactions to egg Absence of sensitization to Ovomucoid indicates: • Tolerance to cooked egg
Ovomucoid – clinical utility “-Quantification of ovomucoid antibodies could be useful in guiding the physician in the decision whether to perform a challenge or not”
Ovomucoid – clinical utility “-For prediction of reaction to heated egg white, ovomucoid was superior” (to egg white)
Ovalbumin – Gal d 2 • The most abundant allergen in egg white (54%) • Heat labile • Highly allergenic
Conalbumin – Gal d 3 • 12% of egg white protein • Heat labile • Present also in egg yolk Conalbumin = Ovotransferrin
Lysozyme – Gal d 4 • Minor allergen • 3.5% of egg white protein • Used as preservative/additive • Occupational allergen (food and pharmaceutical industries)