Allergen products for in vivo diagnosis can be separated into two major groups: Extract-based products prepared from allergenic source material like pollen for diagnosis of immediate-type hypersensitivity (Type I allergy, IgE-mediated) and epicutaneous patch test (PT) preparations for diagnosis of delayed-type hypersensitivity (Type IV allergy, cell-mediated) in patients with suspected allergic contact dermatitis. The gene discussed is IGHE; the disease is allergic disease.