BCL2 is a tumor suppressor gene located in the 18q21 region. BCL2 gene encodes a mitochondrial membrane protein that regulates apoptosis and is expressed in B cells. Translocation of the BCL2 gene is usually recognized in B cell lymphoma. In particular, translocation of t(14;18)(q32.3;q21.3) is present in approximately 80% of follicular lymphoma (FM), 20%-30% of diffuse large B-cell lymphoma In (DLBCL), it rarely occurs in B-cell chronic lymphocytic leukemia (B-CLL). Therefore, the detection of BCL2 translocation by fluorescence in situ hybridization (FISH) may have diagnostic and prognostic significance.