Of note, we detected four patients (P002, P018, P219 and P264) each carrying known variants in TNFRSF13B and a second potentially pathogenic mutation in CTLA4, STAT3 or NFKB1. We currently do not know whether the identified variants in TNFRSF13B (TACI) might influence or affect disease presentation and severity in patients with additional pathogenic mutations in genes associated with other well-defined IEI disorders. The gene discussed is TNFRSF13B; the disease is inborn error of immunity.