SERPING1 and hereditary angioedema: This concept is clearly illustrated by hereditary angioneurotic edema (HAE, specifically HAE Type I, HAE Type III), where a single dysfunctional C1-INH allele (resulting in depleted C1-INH levels) culminates in potentially life-threatening levels of vasopermeability (Späth et al., 1984; Cugno et al., 2009; Hack et al., 2012; Schmaier, 2019; Kajdacsi et al., 2020).