Molecular diagnosis of egg allergy: an update

Hen's egg allergy affects up to 2.5% of young children and is potentially life-threatening. Several phenotypes of egg allergy have been identified, including those who tolerate extensively heated egg in bakery products. Diagnosis and monitoring for resolution often requires oral food challenges, which can result in anaphylaxis. Newer approaches, such as component-resolved diagnostics, microarray analysis and epitope mapping, are being evaluated to determine if these strategies can replace or reduce the need for oral food challenges. Studies suggest that elevated levels of ovomucoid IgE indicate an inability to tolerate extensively heated forms of egg. Egg protein-specific IgE/IgG4 ratios may be helpful in predicting tolerance. Additionally, patients with conformational epitopes to hen's egg are more likely to resolve their allergy compared with those with IgE binding to sequential epitopes. The pairing of microarray technology to epitope mapping is a potential tool to improve diagnosis. This review examines the current body of literature on these tools.