Abnormal expansion over time of hematopoietic cell populations was commonly observed in Eμ-PRMT5 mice, including a Cd5+Cd19+B220dim B-cell population with similarity to the CLL-like disease in Eμ-TCL1 mice33 (Fig. 2d, e and Supplemental Fig. 2A, B). The gene discussed is PRMT5; the disease is B-cell chronic lymphocytic leukemia.