HAE-C1INH-Type1 (approximately 80–91% of HAE cases) is caused by a quantitative deficiency in C1INH protein,2, 3, 4 and HAE-C1INH-Type2 (approximately 9–15% of HAE cases) is caused by a dysfunction in C1INH protein.2 This evidence concerns the gene SERPING1 and hereditary angioedema.