Hereditary angioedema Hereditary angioedema has 3 types: Type 1 (80 to 85%): Characterized by C1 inhibitor deficiency Type 2 (15 to 20%): Characterized by C1 inhibitor dysfunction Type 3 (rare): Characterized by normal C1 inhibitor function and levels Type 1 and type 2 involve mutations of the gene encoding C1 inhibitor.