Patients were included if they had a genetic assay demonstrating a known HAE-nC1-INH–associated variant; or had a family history of angioedema and normal C1-INH level and function, no response to antihistamine treatment, met predefined diagnostic criteria for HAE-nC1-INH, and had been prescribed berotralstat 150 mg daily for at least 6 months. Here, SERPING1 is linked to hereditary angioedema.