However, when analyzing the reactivity to birch we clearly see that peanut-sensitized, non-anaphylactic patients (PS) show a significantly higher level of specific IgE to birch, rBet v 1 and rAra h 8, as compared with patients with severe peanut allergy, which indicates that they are sensitized to peanut due to a cross-reaction between birch pollen and peanuts [8]. This evidence concerns the gene IGHE and peanut allergic reaction.