Lymphopenia (610/μl; RV: 1200-4100*).Low switched memory B cells (0.30%; RV: 3-46*) and CD21 low expansion (48.70%; RV: 2-14*).Absent IgA and IgM; Pre-replacement therapy IgG levels are not available.Reduced proliferation assays.Recurrent respiratory low infections, adenopathies, splenomegaly, atrophic gastritis. The gene discussed is CD40LG; the disease is Splenomegaly.