The clinical spectrum of omega-5-gliadin allergy

Background IgE‐mediated allergy to the wheat protein omega‐5‐gliadin (O5G) is associated with wheat‐dependent exercise‐induced anaphylaxis (WDEIA), where exercise acts as a cofactor, triggering anaphylaxis after wheat ingestion. The wider application of O5G‐specific IgE (sIgE) testing has revealed that the manifestations of O5G allergy extend beyond WDEIA. Aims This study documents clinical manifestations in a large series of patients with sIgE to O5G. Methods A retrospective clinical audit was performed on adult patients with a positive O5G sIgE (>0.35kU/L) between 2007 and 2013 compared with a group who had negative O5G sIgE. Clinical characteristics and skin prick test (SPT) results were examined. Results Sixty‐seven patients were characterised, 26 of whom presented with food‐dependent exercise‐induced allergy, whilst others presented with exercise‐induced symptoms without apparent food association (16/67), idiopathic anaphylaxis (10/67), food‐induced allergic symptoms without exercise (10/67) or recurrent acute urticaria (5/67). Specific IgE to O5G had 91% sensitivity and 92% specificity for wheat‐related allergic symptoms. SPT had sensitivity of 92% and specificity of 84%. Conclusion WDEIA is the most common manifestation of O5G allergy, but patients may present with a variety of allergic manifestations, and wheat allergy is not always obvious on history. Non‐exercise cofactors or a lack of cofactors were identified in many patients. A distinctive feature of this allergy is that despite regular wheat ingestion, allergic reactions to wheat occur infrequently. Testing for sIgE to O5G should be considered in patients presenting with exercise‐induced urticaria/anaphylaxis, idiopathic anaphylaxis and recurrent acute (but not chronic) urticaria.