Although a number of studies have indicated Ara h 2 to be the more potent of these two allergens 39–41, Ara h 1 also plays a major role in the pathogenesis of peanut allergy, with numerous studies reporting strong correlations between symptom severity and IgE reactivity to both Ara h 1 and Ara h 2 42–47. This evidence concerns the gene IGHE and peanut allergic reaction.