Investigating the connection between the prevalence of hypersensitivity and the type of C1-INH-HAE, we found that out of our 97 patients with type I C1-INH-HAE, 61 had some type of hypersensitivity (62.9%), while this ratio was 66.6% (6/9) in the patients with type II C1-INH-HAE. This evidence concerns the gene SERPING1 and hereditary angioedema.