Forms of hereditary angioedema that occur due to mutations in the gene for complement C1 inhibitor protein. Type I hereditary angioedema is associated with reduced serum levels of complement C1 inhibitor protein. Type II hereditary angioedema is associated with the production of a non-functional complement C1 inhibitor protein. The disease is Monarch Disease Ontology id MONDO_0033946 (hereditary angioedema with C1Inh deficiency). Also known as: angioedema, hereditary, 1 and 2, angioedema, hereditary, type 1/2.