<s>[INST] context: Angioedema (angioedema/ Quincke’s edema/ angioneurotic edema) 

Characterized by rapid swelling (edema) of the dermis, subcutaneous tissue, mucosa and submucosal tissues. It is very similar to urticaria, but urticaria, commonly known as hives, occurs in the upper dermis
Angioedema is classified as either hereditary or acquired.

a) Acquired angioedema (AAE) can be immunologic, nonimmunologic, or idiopathic.
It is usually caused by allergy and occurs together with other allergic symptoms and urticaria.
It can also occur as a side effect of certain medications, particularly ACE inhibitors.
b) Hereditary angioedema (HAE) exists in three forms, all of which are caused by a genetic mutation inherited in an autosomal dominant form.
i) Types I and II are caused by mutations in the SERPINGl gene, which result in either diminished levels of the C1-esterase inhibitor protein (type I HAE) or dysfunctional forms of the same protein (type II HAE).
ii) Type III HAE has been linked with mutations in the F12 gene, which encodes the coagulation protein factor, XII.

All forms of HAE lead to abnormal activation of the complement system.
The end product of this cascade, bradykinin, is produced in large amounts and is believed to be the predominant mediator leading to increased vascular permeability and vasodilation that induces typical angioedema "attacks". [/INST] question: Angioedema is seen due to deficiency of? | options: A: Angiotensin converting enzyme B: C1 esterase inhibitor C: Histamine D: Angiotensin 1 | answer: B </s>