Description

Angioneurotic edema (AE) occurs as a result of a C1-inhibitor deficiency, which may be either quantitative or qualitative. The deficiency results in a lack of inhibition to a series of serum proteases, which then act unchecked. The disorder may be either hereditary or acquired.


 

Targets of C1-inhibitor are proteases that include:

(1) complement system: C1r and C1s

(2) contact system: Factor 12a and kallikrein

(3) coagulation cascade: Factors 11a, 12a and 12f

(4) fibrinolysis: plasmin

 

Clinical features of deficiency state:

(1) sudden onset of recurrent, subepithelial swellings which are circumscribed and non-pitting and which may involve the extremities, face, mouth, larynx and bowel wall.

(2) family history in the hereditary form

(3) absence of pruritus and accompanying urticaria

(4) recurrent gastrointestinal colics, with pain, nausea, vomiting and/or watery diarrhea

(5) CNS symptoms including headaches, hemiparesis or seizures

 

Factors precipitating attacks:

(1) stress

(2) minor trauma, dental procedures or surgery

(3) insect stings

(4) food or alcohol

(5) drugs, especially angiotensin-converting enzyme (ACE) inhibitors, oral contraceptives or estrogen replacement therapy

(6) menstruation or pregnancy (associated with increased estrogen levels)

(7) nothing specific

 

Pathogenesis:

(1) hereditary (HAE)

(1a) autosomal dominant disorder with a frequency of 1 in 50,000 persons

(1b) de novo mutations

(2) acquired (AAE)

(2a) paraprotein associated (resulting in a Type I pattern)

(2b) antibodies to C1-INH, typically as autoantibodies associated with CLL or other lymphoproliferative disorder (resulting in a Type II pattern)

Type

C1-INH antigen

C1-INH functional activity

C4 Level

C1q Level

Hereditary Type I

decreased

decreased

decreased

normal

Hereditary Type II

normal or increased

decreased

decreased

normal

Acquired Type I

decreased

decreased

decreased

decreased

Acquired Type II

normal or increased

decreased

decreased

decreased

after Table 1, page 26, Ebo and Stevens (2000)

 


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