A pre-malignant condition, defined as IgM monoclonal gammopathy of undetermined significance (MGUS) may precede the WM stage disease, being characterized by less than 10% lymphoplasmacytic BM involvement, less than 3g/dL of monoclonal IgM, together with lack of clinical signs or symptoms secondary to the WM disease. The gene discussed is CD40LG; the disease is monoclonal gammopathy.