Abstract

Yam (Dioscorea opposita THUNB.) is known to induce allergy-like symptoms due to the presence of choline in yam. But yam allergy is not well characterized, because an allergen extract for skin test and a system for detection of anti-yam IgE antibody were not commercially available. The aim of this paper is to report the 7 cases of yam allergy with positive IgE antibody detected by UniCAP specific IgE. Allergic symptoms after ingestion of yam included systemic erythema and urticaria, or angioedema on the face, as well as respiratory symptoms (n=2, cough and wheeze) and gastrointestinal symptoms (n=1, vomit and diarrhea). Patients were also reacted to heat processed foods such as cookies containing yam. Seven patients without IgE antibody to yam only had mild and transient rash around the mouth, considered to be due to the presence of pseudo-allergen in yam. In conclusion, detection of IgE antibody by UniCAP specific IgE was useful for the diagnosis of yam allergy.