A history or family history of allergic rhinitis or atopic dermatitis, or the presence of atopy (demonstrated by either a positive skin prick test or specific IgE to one or more aeroallergens) increases the chance that a patient with respiratory symptoms has allergic asthma, but these features are not specific for asthma, and asthma may be non-allergic. This evidence concerns the gene IGHE and asthma.