The study was designed as long-term cohort study specifically addressing the correlation between homozygous and heterozygous states and complement activity, the impact of complete and partial CD on the long-term outcome in patients with CD (excluding HAE), correlation between specific mutations in C2 (including 2 novel mutations) and complement activity, as well as prevalence and clinical manifestations of HAE. This evidence concerns the gene C2 and hereditary angioedema.