The SERPING1 gene encodes a highly glycosylated plasma protein involved in regulating the complement cascade. The complement C1 inhibitor (C1-INH) produced by this gene is a crucial multifunctional plasma glycoprotein that plays key roles in various biological systems, including the complement system, coagulation system, and fibrinolytic system. Despite its essential role in multiple physiological processes, C1-INH is known for its defect in hereditary angioedema (HAE). HAE, also known as C1 inhibitor deficiency, is a rare and debilitating disease. Patients with HAE experience severe periodic swelling, primarily affecting the arms, legs, face, intestines, and respiratory tract. The prevalence of HAE is approximately 1 in 50,000 individuals, and if left untreated, it can lead to a mortality rate of 20% to 30% when it affects the respiratory tract ^[1]. SERPING1 is the primary pathogenic gene in hereditary angioedema (HAE). Mutations in this gene lead to the deficiency or dysfunction of complement C1 inhibitor (C1-INH). As a result, there is an excessive secretion of vasoactive peptides, causing fluid leakage into tissues such as mucous membranes and subcutaneous areas, leading to localized swelling and edema ^[2]. As an essential protein for maintaining immune balance and preventing excessive inflammatory responses, C1-INH has been gaining widespread attention due to its pathogenic mechanisms, as well as its role in drug development. Serping1 gene-deficient mice serve as crucial tools for researching C1 inhibitor deficiency.

This model is Serping1 gene knockout mice, where the Serping1 gene homologous to the human SERPING1 gene has been knocked out. In Serping1 KO mice, C1-INH protein is deficient. This leads to a significant increase in vascular permeability, which closely mirrors the pathogenic mechanisms and clinical symptoms observed in human HAE patients. The homozygous mice are viable and fertile. Serping1 KO mice serve as valuable tools for studying the pathogenesis of HAE and screening therapeutic drugs.