PIK3CD and common variable immunodeficiency: Specific variants in these genes as well as in others not listed in the OMIM database (NOD2, MSH5, TNFRSF13B, HLA) have been reported to confer susceptibility to the disease or to originate similar phenotypes to CVID (CTLA4, PLCG2, PIK3CD, PIK3R1), blurring even more the boundaries that define this disorder.