Guidelines state that HAE attacks should be treated early with intravenous (IV) plasma-derived C1-INH and recombinant human C1-INH, plasma kallikrein inhibitor ecallantide administered subcutaneously by a health professional, or self-injected subcutaneous (SC) bradykinin B2 receptor antagonist icatibant, and that early treatment provides far better clinical outcomes than late treatment [11]. The gene discussed is KLK4; the disease is hereditary angioedema.