CD53 and B-cell chronic lymphocytic leukemia: CLL patients with unmutated (UM-CLL) immunoglobulin heavy chain variable (IGHV) region genes (>98% homology to germline sequences), increased expression of the CD38 cell surface antigen, or of the 70-kd zeta-chain T-cell receptor–associated protein kinase (ZAP-70) experience a shorter therapy-free interval, a more aggressive clinical course, and a shorter survival [6-8].