Novel mutations in hyper-IgM syndrome type 2 and X-linked agammaglobulinemia detected in three patients with primary immunodeficiency disease.

Four pathogenic variants in AICDA and BTK were confirmed to cause different forms of hyper-IgM syndrome type 2 (HIGM2) and X-linked agammaglobulinemia (XLA); two were novel mutations that have never been reported previously. This is the first report of HIGM2 caused by AICDA deficiency in a patient from the Chinese mainland.