These include infections (Lyme disease, human immunodeficiency virus, Helicobacter pylori colonization, syphilis, mononucleosis, rubeola, toxoplasmosis, varicella, hepatitis); medications (oral contraceptives, penicillin, angiotensin-converting enzyme inhibitors); cryoglobulinemia; Hymenoptera stings; hematologic malignancies; and immunotherapy.2,7,12 A familial variant with autosomal-dominant transmission has also been identified and tends to portray a higher morbidity.7,9 See Figure 2 for a summary of secondary causes of chronic urticaria. This evidence concerns the gene ACE and infectious mononucleosis.