To date, it has been reported that approximately 30%–40% of patients with Waldenstrom’s macroglobulinemia (WM)—a type of lymphoplasmacytic lymphoma (LPL) exhibiting BM involvement and Immunoglobulin M IgM monoclonal gammopathy—carry mutations in heterozygosis of CXCR4 [84,85,86]. The gene discussed is CXCR4; the disease is monoclonal gammopathy.