In addition, a severe de-novo IgA deficiency (IgA < 10 mg/dl) occurred in four patients (two of them were those with severe hypogammaglobulinemia), independently of the number of anti-CD20 infusions, whilst only one patient had low IgM at last follow-up (Figures 1H,I, 2H,I). Here, CD40LG is linked to selective IgA deficiency disease.