The strong association between SIgAD and celiac disease complicates clinical practice both by the fact that most laboratories use IgA-based tests (anti-tissue transglutaminase and/or anti-endomysial antibodies) for the diagnosis of CD and by the low susceptibility of these individuals to manifest gastrointestinal symptoms, inversely correlated with the risk of underdiagnosis, but without clear evidence of the impact of untreated CD on the incidence of lymphomas. The gene discussed is CD79A; the disease is selective IgA deficiency disease.