Hereditary angioedema due to C1-INH deficiency (C1-INH-HAE), the prototype of primary angioedema, is an autosomal dominant disease caused by deleterious mutations in the SERPING1 gene, leading to quantitative and/or functional C1 inhibitor (C1-INH) deficiency [2]. The gene discussed is SERPING1; the disease is hereditary angioedema.