Further, we compared female (F) and male (M) patients’ age at occurrence of their first HAE symptoms and the length of diagnostic delay using the Mann–Whitney U-test; their complement profile at diagnosis (total complement activity, C1q, C3, C4, C1-INH antigenic concentration, C1-INH functional activity) using t-tests; and their disease severity defined as the average yearly attack rates using the Mann–Whitney U-test. The gene discussed is C4A; the disease is hereditary angioedema.