Abstract: Objective: To identify the pathogenic gene in a family with type II hereditary angioedema (HAE-II). Methods: Clinical data of the family were collected. Enzyme-linked immunosorbent assay (ELISA) was used to detect the concentrations of complement C4, C1 inhibitor (C1-INH) and C1-INH function in the proband and one family member suspected of having HAE. Whole-exome sequencing was performed on the proband and two family members to identify candidate gene mutation sites, which were then verified by Sanger sequencing. Results: A survey of 10 members across 3 consecutive generations of the family found that 4 had suspicious clinical manifestations, including the proband, the proband's cousin, cousin sister, and aunt. The serum C4 level and C1-INH function of the proband and cousin sister were lower than the lower limit of the normal range, while the C1-INH concentration did not decrease, so they were diagnosed with HAE-II. Genetic testing revealed that both the proband and his aunt carried a heterozygous mutation in the serpin family G member 1 (SERPING1) gene: c.1396C＞T (p.R466C). The proband was treated with lanadelumab, and no edema attack occurred during 1 year of follow-up. Conclusion: The heterozygous mutation c.1396C＞T in the SERPING1 gene is the cause of hereditary angioedema in this family, and lanadelumab treatment can achieve good results.

Key words: hereditary angioedema, serine protease inhibitor G1, gene mutation, lanadelumab