Hereditary angioedema is a rare disorder identified by episodes of swelling under the skin, gut lining, and the lungs. Learn its triggers, treatments and more., INTRODUCTION. Hereditary angioedema (abbreviated HAE throughout this review) is a rare autosomal dominant disorder characterized by recurrent episodes of well-demarcated angioedema without urticaria, which most often affects the skin or mucosal tissues of the upper respiratory and gastrointestinal tracts., Hereditary angioedema (HAE) is an autosomal dominant disease caused by the lack of or a dysfunctional C1-inhibitor protein. For this reason, the nomenclature has been developed to replace the initial use of type 1, 2, or 3 HAE. Instead, the names are HAE with deficient C1-inhibitor (type 1), HAE with dysfunctional C1-inhibitor (type 2), and HAE with normal C1-inhibitor. Though unique in the , , , .