Hereditary Angioedema is classified into three types based on what problem the genetic defect causes.

• Type I - Low levels of C1-INH in the body; this is the most common form of HAE and accounts for ~85% of people with HAE.
• Type II – Normal or elevated levels of C1-INH, but C1-INH is dysfunctional; this accounts for ~15% of people with HAE.
• HAE with Normal C1-INH (formerly known as HAE Type III) - Normal and functioning levels of C1-INH; this type of HAE is extremely rare and not well understood.