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- BCL2-IGH Fusion Gene Detection
- BCL2 Gene Rearrangement
Major breakpoint region (MBR) and minor cluster region (mcr)
The majority of follicular lymphomas are characterized by t(14;18) (q32;q21). This translocation joins the BCL2 gene on chromosome 14, resulting in the overproduction of the BCL2 protein, a potent apoptosis inhibitor. There are two common breakpoint regions involving BCL2 with approximately 65% of the breakpoints occurring at the major breakpoint region (MBR) and approximately 10% occurring at the minor cluster region (mcr). The BCL2-IGH translocation is also observed in 20% to 30% of diffuse large B-cell lymphomas. The ability to detect the t(14;18) translocation by means of polymerase chain reaction (PCR) allows for rapid assessment of the presence of this translocation. This is of significant clinical utility for defining the cause of the lymphoma and for monitoring minimal residual disease.
The absence of a detectable fusion product does not exclude the presence of a rearrangement outside of the two breakpoint regions evaluated, or the presence of a B-cell lymphoma without an underlying BCL2-IGH translocation. In addition, it is important to note that the BCL2-IGH gene rearrangement has also been detected at low levels in some apparently benign hyperplastic lymphoid tissues.
Polymerase chain reaction (PCR); gel electrophoresis
The protein coded for by the oncogene, BCL2, acts by suppressing the cell death program or apoptosis.1 Apoptosis occurs in all cells but is especially important in immune and hematopoietic cells, which have a high cell turnover rate. When the BCL2 gene is overexpressed, it will act to prevent apoptosis and possibly may render cells resistant to cell death by irradiation and certain chemotherapeutic agents.2,3 A translocation between immunoglobulin genes (heavy chain or light chain genes) and BCL2 results in the overexpression of BCL2 protein and thus the expansion of B cells due to halting cell death. This type of translocation is found in 80% to 90% of follicular lymphomas, 30% of large diffuse lymphomas, and 50% of undifferentiated lymphomas.4
Whole blood, bone marrow, fresh or frozen tissue, fixed-cell pellet
7 mL whole blood, 2 mL bone marrow, or 0.5 g tissue
3 mL whole blood
Specimens should arrive in the laboratory within 48 hours of collection. Indicate date and time of collection on the request form. To avoid delays in turnaround time when requesting multiple tests on frozen samples, please submit separate frozen specimens for each test requested.
Maintain specimen at room temperature. Some specimen types may be submitted frozen; call 800-345-4363 for instructions.
Causes for Rejection
Specimen more than 48 hours old; clotted blood
For testing on material other than specimen types listed, call the laboratory. Please direct any questions regarding this test to oncology customer service at 800-345-4363.
|Order Code||Order Code Name||Order Loinc||Result Code||Result Code Name||UofM||Result LOINC|
|480566||BCL2-IGH Gene Rearrangement||480570||bcl-2 Translocation, Lymphoma||21095-5|
|480566||BCL2-IGH Gene Rearrangement||480572||Methodology:||49549-9|
|480566||BCL2-IGH Gene Rearrangement||489033||Director Review||72486-4|