TNFRSF13B and common variable immunodeficiency: In five patients we found four variants of TNFRSF13B, but we considered as causative of the CVID phenotype only the mutations found in a compound heterozygous (in one patient) and homozygous (in another patient) state and not those in heterozygous form, in line with what is reported in the literature, as mentioned in the discussion.