Chronic lymphocytic leukemia (CLL) is a mature B-cell clonal proliferative tumor characterized by lymphocyte aggregation in peripheral blood, bone marrow, spleen and lymph nodes. Chronic lymphocytic leukemia is also diagnosed in patients with persistent (3 months) peripheral blood B lymphocyte ≥ 5 × 109 / L (e.g. peripheral blood B cell < 5 × 109 / L accompanied by hematopenia caused by bone marrow infiltration or disease-related symptoms). By fluorescence in situ hybridization, about 80% of chronic lymphoblastic leukemia patients have chromosome abnormalities, the most common deletions are deletions of chromosome 13 long arm del (13q14.1), chromosome 12 deletions or trisomy, and chromosome 17 short arm deletions del (17p).