COL18A1 and hereditary angioedema: HAE may be associated with mutations in the C1-inhibitor (C1-INH) protein gene (HAE-C1-INH) and subclassified as HAE-C1-INH Type 1 (deficient C1-INH) or HAE-C1-INH Type 2 (defective C1-INH), or it may be associated with other mutations in patients with normal C1-INH levels and function (HAE-nC1-INH).