Genetic Diversity and IgE-Recognition of Hazelnut Oleosins: A Proteogenomic Investigation across Cultivars

Hazelnut ( Corylus avellana L.) is a significant global food source and a widely consumed nut in the food industry. Hazelnut allergy is prevalent, with oleosins recently identified as allergenic proteins. Genetic diversity among hazelnut varieties may lead to variety-specific differences in IgE-binding properties, offering the potential for therapeutic strategies using hypoallergenic varieties for desensitization. This study evaluated the allergenic potential of 14 hazelnut varieties using a proteogenomic approach. Genomic analysis of six genotypes revealed polymorphisms in three oleosins with greater variability in regulatory regions. Sanger sequencing of the Cor a 15 oleosin gene's CDS/promoter region was conducted for all varieties. Minor differences were observed in the genes encoding oleosins, while variability was more pronounced in the regulatory regions. However, IgE reactivity was similar across all varieties, with Cor a 15 being the main IgE-reactive oleosin. A conventional exclusion diet remains the most reliable method for managing allergic reactions.