The expression of FCGR2A (also known as FcγRIIA or CD32, involved in “Fc gamma R-mediated phagocytosis”) was significantly decreased in primary monocytes of the XLA patients which is consistent with the findings about decreased expression of FCGR2A in monocytes from XLA patients due to BTK deficiency13. Here, BTK is linked to Bruton-type agammaglobulinemia.