Chronic lymphocytic leukemia (CLL) is a neoplasia of B lymphocytes, a type of white blood cell, characterized by a slow accumulation of these cells in the bone marrow and blood. As the disease progresses it causes deficiencies in the body's defenses, bone marrow failure, and finally the invasion of other organs by the tumor cells. CLL is one of the most frequent tumors in Western countries, representing 35% of all leukemias with an incidence of 3-7 per 100.000 inhabitants and reaching 12-15/100.000 in people over 60 years.
The disease is clinically and biologically heterogeneous. Some patients have a long clinical evolution with a stable disease and a normal lifespan, whereas others follow a progressive course with an average survival of 5-8 years. This heterogeneity is due in part to the existence of two major molecular subtypes of the disease, characterized respectively by the presence or absence of somatic mutations in the immunoglobulin genes. Different genetic alterations have been identified associated with particular clinical presentations and evolution but the specific genes and their alterations responsible for the evolution of the disease are not well known. There is also evidence of a genetic predisposition, but the initiating genetic alterations are largely unknown in both sporadic and inherited cases. Today, there is no curative therapy for CLL.