The biological features of Mut/Del and Mut/noDel CLL patients were significantly different, since adverse prognostic factors, such as CD38 positivity (P = 0.006), UM-IGHV gene status (P = 0.003), and NOTCH1 mutations (P = 0.0415), were less frequently observed in the Mut/noDel patients’ group. The gene discussed is CD38; the disease is B-cell chronic lymphocytic leukemia.