In addition to this, certain monogenic causes of the CVID phenotype, such as those affecting NFKB1, NFKB2, TNFSF12 (TWEAK), TNFRSF13B (TACI) and IKZF1 (IKAROS), have been individually reported with pronounced viral illnesses [55,56,57,58,59]. This evidence concerns the gene TNFRSF13B and common variable immunodeficiency.