It is currently licensed for the treatment of the adult with non-Hodgkin’s lymphoma (NHL), chronic lymphocytic leukemia (CLL) rheumatoid arthritis, granulomatosis with polyangiitis and microscopic polyangiitis.[1–5] The therapeutic efficacy of rituximab is based on the B-cell depletion mediated by the selective binding of CD20 receptors expressed on the surface of these cells.[1] By causing the depletion of B lymphocytes, rituximab interferes with humoral immunity, and the risk of infections represent one of the major safety concerns associated with its use. This evidence concerns the gene MS4A1 and B-cell chronic lymphocytic leukemia.