,2 Birch pollen with the major allergen Bet v 1 is a common cause for allergic rhino conjunctivitis and mild asthma in Northern and Central Europe, affecting 8-16 % of the European population.3, 4, 5 Mast cells and basophils are characterized by the expression of the high-affinity receptor for IgE, FcεRI, and, hence, represent the central effector cells of the IgE-mediated allergy.6 The gene discussed is IGHE; the disease is asthma.