In a phase III trial in chronic lymphocytic leukemia (CLL) comparing alemtuzumab (anti-CD52) to chlorambucil, the risk of developing PCR-positive CMV in the alemtuzumab arm was 69%, with 15.6% of these patients displaying symptomatic CMV infections without end organ involvement. The gene discussed is CD52; the disease is B-cell chronic lymphocytic leukemia.