CD40LG and food allergy: Total IgG deficiency was found in 20.6%; 19.3% had IgM deficiency (13.5% had elevated IgM antibodies, not in the range of Waldenstroms macroglobulinemia); 15.9% had IgA deficiency (which can increase the incidence of food allergies), while more than 85% had combined IgG subclass deficiencies, 1–4 (see Table 1).