A number sign (#) is used with this entry because this form of common variable immunodeficiency (CVID, https://omim.org/entry/240500), referred to here as CVID2, is caused by heterozygous, homozygous, or compound heterozygous mutation in the TNFRSF13B gene (604907), which encodes the transmembrane activator and CAML interactor (TACI), on chromosome 17p11.2.
Selective IgA deficiency-2 (IGAD2; 609529) can also be caused by mutation in the TNFRSF13B gene.
For a general description and a discussion of genetic heterogeneity of common variable immunodeficiency, see CVID1 (607594).