A classification of patients according to the number of total lymphocytes in blood (Fig. 5b) and the percentage of malignant CD19 + CD5+ B cells (Fig. 5c) showed a direct correlation with overexpression of RRAS2, i.e., the group of patients with highest lymphocytosis and malignant cell content has the highest overexpression of RRAS2. The classification of patients that present premalignant MBL versus full-blown CLL is based on the degree of lymphocytosis (threshold at 5 × 106 lymphocytes/mm3). Here, CD19 is linked to B-cell chronic lymphocytic leukemia.