Diagnosing HAE

How is Hereditary Angioedema (HAE) diagnosed?

Most cases of angioedema turn out to not be HAE, because most swelling attacks are typically allergic reactions, or swellings caused by something other than C1-inhibitor deficiency.

Laboratory analysis of blood samples or genetic testing is required to establish the HAE diagnosis. There are two specific blood tests that confirm HAE:

  1. C1-inhibitor quantitative (antigenic)
  2. C1-inhibitor functional

Angioedema Types:

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    Comprehensive Table of Angioedema Types

    Get the full overview with our Comprehensive Table of Angioedema Types.

    You can download the table here (pdf)

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    Type I HAE - 85 % of patients

    The most common form of the disease–Type I–is characterized by low quantitative levels of C1-inhibitor and affects about 85% of patients.

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    Type II HAE - 15 % of patients

    Type II HAE affects the other 15% of patients who have normal or elevated levels of C1-inhibitor, but the protein does not function properly.

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    HAE with Normal C1 Inhibition

    Several investigators have noted a familial (and therefore inherited) angioedema in patients with normal levels of C1-inhibitor. Now found under the designation of “HAE with Normal C1 Inhibitor”, this form of angioedema is yet to be fully understood.
    In women, swellings have been correlated with pregnancy or the use of oral contraceptives; however, affected male family members have also been identified.

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    Factor XII

    Some scientists believe that a mutation in the gene for human coagulation Factor XII may be a potential cause of swelling in these patients with familial estrogen-exacerbated angioedema.

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