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FAQ: Disease causes
Answers on frequently asked questions about disease causes. Definitions can be looked up in the glossary.
How many people are affected by HAE?
Exact figures regarding the incidence of HAE are not available. It is estimated that about 1 in 10,000 to 1 in 50,000 people are affected worldwide. Experts assume that only 1 in 2 people with HAE are given the correct diagnosis.What causes hereditary angioedema?
HAE is caused by a genetic defect on chromosome 11, which leads to a deficiency of the protein C1 esterase inhibitor (C1-INH). This protein is part of a system known as the complement system, which is involved in the complex interaction leading to immune and inflammatory reactions in the body. Among other things, C1-INH reduces production of the tissue hormone bradykinin. If insufficient C1-INH is available, bradykinin concentrations increase and an episode of swelling can occur.There are three types of HAE. Type I is the most common (approx. 80-85% of cases) and involves a C1-INH deficiency resulting from insufficient production of the enzyme. Type II affects approx. 15% of patients and involves normal or even elevated C1-INH concentrations but reduced C1-INH activity (function). The third form of the disease is very rare. Unlike the other two subtypes of HAE, this subtype is not associated with a C1-INH deficiency and research into the exact causes is ongoing.
What triggers an episode of HAE?
Episodes of HAE often occur without an obvious trigger.However, in some cases, a cause can be identified. For instance, infections, minor injuries and mechanical stimuli such as pressure can create favourable conditions for an episode.
Dental procedures or surgery to remove the tonsils are particularly critical, as they can cause swelling in the larynx. Emotional and mental stress can also trigger an episode.
Hormonal factors are another known cause of episodes of HAE. For example, the frequency of episodes can be higher in women taking drugs containing oestrogen (the pill, products for menopausal complaints) or who are menstruating. Certain drugs that lower blood pressure, such as ACE inhibitors, can also trigger episodes of swelling.
What does the fact mean that HAE is a hereditary disease?
The defect on chromosome 11 that is responsible for HAE is equally common in men and women and can be passed on by both sexes. Both men and women with HAE can have children. As HAE is an autosomal dominant hereditary disease, there is a 50% risk of a child inheriting the disease from the affected parent. Male and female offspring are at equal risk of inheriting HAE.| Frequently inquired |
Author: Jerini AG
Source: HAE-Network Status: 3/08 This FAQ is frequently updated. Please send us your comments or suggestions by e-mail. |
