The diagnostic was confirmed by a biopsy in two patients with CID and CVID and by a “no-biopsy approach” (i.e., TGA-IgA values ≥10 times the upper limit of normal and positive endomysial antibodies (EMA-IgA) in a second serum sample) in two patients with HAE/C1-inhibitor deficiency. The gene discussed is CD79A; the disease is C1 inhibitor deficiency.