Selective IgA deficiency and the HLA-B8 antigen. Report of two cases with familial data.

Two patients had IgA deficiency, giardiasis, and the HLA-B8 antigen. The family of patient 1 included members with juvenile-onset diabetes mellitus, adrenal insufficiency, pernicious anemia, and hypothyroidism, a combination of unusual diseases that has been reported previously to occur as a syndrome with IgA deficiency and the HLA-B8 antigen. This coincidence makes it likely that these two patients and the one family previously described have a common pathogenic base, the inheritance of an abnormal immune-response gene that is acquired with the HLA-B8 antigen as a result of genetic dysequilibrium.