Using multi parametric flow cytometry, we found that CD19(+) B-cells expressed CD5 (dim), CD20 (dim), CD23, CD38, kappa light chain restriction, surface IgM and IgD, and also were negative for CD10, CD22, FMC7 and lambda, compatible with a diagnosis of B-CLL (Figure 2). This evidence concerns the gene MS4A1 and B-cell chronic lymphocytic leukemia.