RESUMO
OBJECTIVE: To explore the genetic pathogenesis of X-linked agammaglobulinemia in two patients for clinical diagnosis and family counseling. METHODS: Data was collected from the patients' family including clinical information, blood immunoglobulin level, as well as classification and subgrouping of B lymphocytes. Gene mutations were screened by whole exome sequencing (WES) through next-generation sequencing (NGS), the result was verified with Sanger sequencing. RESULTS: A BTK c.1627T>C (p.Ser543Pro) variant was found in the pedigree. The phenotype and variant have co-segregated in the pedigree. The variant was not found in population database. The variant has affected in the kinase domain which contained no benign variants and is harmful as predicted through bioinformatic analysis. CONCLUSION: BTK c.1627T>C (p.Ser543Pro) is a pathogenic variant contributing to X-linked agammaglobulinemia in this pedigree. Above finding has provided reproduction guidance for this family.