CD40LG and agammaglobulinemia: The most recent International Consensus Document (ICON) guidelines list five criteria for CVID diagnosis [10]: (1) IgG level less than two standard deviations for two measurements more than three weeks apart; (2) either low IgA or low IgM, (3) poor antibody responses to vaccination, (4) patient age above four years, (5) no secondary causes of hypogammaglobulinemia.