In a family with hereditary angioedema (HAE), tests can be done to see whether other family members have the disorder. If one parent is affected, then all children and siblings of that parent should be tested. This involves running blood tests. The first test will be to detect levels of a protein called C4 complement. Another blood test is performed to detect low levels of C1 inhibitor. For patients with HAE type I (85% of patients), the C4 level and C1 inhibitor levels are typically low. For patients with HAE type II (15% of patients) the C4 level is typically low, however, the C1 inhibitor level may be normal or high, but it is not functioning correctly.
If the specific changes in the SERPING1 gene are known then molecular genetic testing can be used. These tests look for changes in the SERPING1 gene. However, such testing is usually not necessary.
