Follicular lymphoma (FL) is a low-grade malignant B-cell tumor originating from the follicular germinal center. FL is a common type of non-Hodgkin lymphoma (NHL), accounting for approximately 10% of NHL cases in China and 25%–45% of NHL cases in Europe and the United States.

BCL2 is a tumor suppressor gene located on chromosome 18q21. Approximately 80%–85% of FL cases exhibit BCL2/IGH rearrangements, resulting from the t(14;18)(q32;q21) translocation, which causes the fusion of the BCL2 proto-oncogene with the IGH gene. BCL2/IGH rearrangements are associated with reduced survival rates and poor prognosis;

In addition to primarily fusing with the IGH gene, BCL2 has also been found to fuse with other genes (such as AFF3, IGHL, and IGK);

BCL2 gene breaks can be used in conjunction with MYC gene breaks for the diagnosis of double-hit lymphoma.