Background: Acquired angioedema with C1-inhibitor deficiency (AAE-C1-INH) is a rare condition resembling hereditary angioedema (HAE), but with low or dysfunctional C1-inhibitor (C1-INH) resulting from either due to autoantibody binding or lymphoproliferative diseases, mainly lymphatic malignancies. Here, SERPING1 is linked to hereditary angioedema.