These are included in the assay: to prove that the skin is capable of producing a reaction [19], to assess whether reactivity to histamine is correlated with sensitivity to the tested allergens [20], to detect insufficient lancet penetration leading to false negatives, to brisk lancet handling resulting in false positives (false negative/positive IgE sensitization status), and to prevent e.g. patients suffering from dermatographic urticaria from being falsely diagnosed with an allergy [15,16,21]. This evidence concerns the gene IGHE and allergic disease.