D1.71 - Can an allergist predict the development of allergies? A Clinical case of dizygotic twins with divergent outcomes
Case report
Prediction of allergic diseases remains a central and still unresolved issue in clinical allergology. The global prevalence of allergy continues to grow, reflecting the complex interactions between genetic predisposition and environmental exposure. The hygiene hypothesis, suggesting that reduced microbial stimulation in early life promotes allergic sensitization, remains one of the most widely discussed explanatory concepts. However, translating these theoretical models to individual-level risk prediction remains difficult.
Objective:To demonstrate the challenges and uncertainties of allergy prediction, even among genetically related individuals reared in identical environments.
Case presentation:Patient A., a 9-year-old boy, has been followed since infancy for severe atopic dermatitis. He was exclusively breastfed from birth, but due to persistent and extensive skin symptoms, transitioned to formula feeding at 10 months of age. Simultaneously, a preventive “hypoallergenic” diet was implemented, excluding eggs, dairy products, nuts, and fish. During later dietary expansion trials, he experienced acute hypersensitivity reactions (urticaria and angioedema) to multiple food items. Currently, he avoids eggs, cashews, and kiwi. He remains under medical observation for atopic dermatitis, allergic rhinitis, bronchial asthma, and multiple food allergies.
His dizygotic twin sister, patient K., was raised in the same home environment without dietary restrictions or special allergen avoidance. Today, patient K. is completely healthy and has no clinical signs of allergic disease.
This clinical case clearly illustrates the limited prognostic potential of existing allergy risk models. Despite the close similarity of genes and environmental conditions, the twins demonstrate a globally distinct personal allergoanamnesis. Possible factors contributing to this discrepancy may include gender-related differences, the role of dietary modulation at an early age, and the potential iatrogenic effects of overly restrictive preventive nutrition strategies.
Conclusion:The presented case reinforces the complexity of allergy development and the insufficiency of current tools for individual prognosis. Even among close relatives, allergic manifestations may develop in completely different ways. This observation supports the need for more refined biomarkers and deeper understanding of early immune programming
