CD40LG and severe combined immunodeficiency: Parvaneh L et al. studied 38 PID patients including severe combined immunodeficiency (SCID), common variable immunodeficiency (CVID), X-linked agammaglobulinemia (XLA), and hyper-IgM (HIgM) syndrome with chronic diarrhea and found different infectious agents such as Rotavirus group A, Giardia lamblia, salmonella spp and Candida albicans as the most important viral, parasitic, bacterial and fungal agents (69).