**1. Introduction**

With an age-adjusted incidence of 4–5 per 100,000 population, chronic lymphocytic leukemia (CLL) is the most common type of leukemia in developed countries. The median age at diagnosis is 72 years, and more men than women (2:1) are affected [1]. CLL is one of the B-cell chronic lymphoproliferative disorders. It is characterized by a progressive accumulation of functionally incompetent lymphocytes, which are usually monoclonal in origin.
