bcl-2/JH t(14;18) Gene Rearrangement, |
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Test Highlights |
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Clinical Use
| • | Diagnose B-cell lymphoma including follicular lymphoma and other B-cell lymphomas harboring bcl-2, t(14;18) |
| • | Determine prognosis for patients with diffuse large B-cell lymphomas |
| • | Monitor minimal residual disease (MRD) |
| • | Predict early relapse |
Clinical Background
The bcl-2 gene translocation t(14;18), a rearrangement of the bcl-2 proto-oncogene on chromosome 18 with the immunoglobulin heavy chain region on chromosome 14, leads to deregulated BCL-2 production and interferes with normal apoptosis. The majority of the breakpoints on chromosome 18 are tightly clustered in the major breakpoint cluster region (mbr) and minor cluster region (mcr), although some fall outside of these areas.
The t(14;18) translocation is characteristic of B-cell lymphomas, occurring in up to 90% of follicular lymphomas. It is also found in 20% to 30% of diffuse large B-cell lymphomas, where it is an indicator of poor prognosis. The
bcl-2/JH assay is useful for establishing diagnosis, predicting prognosis, monitoring therapeutic response, and detecting MRD or recurrent disease.
Method
In this quantitative real-time polymerase chain reaction (PCR)-based assay, DNA is amplified using primers specific for the mbr and the mcr within the bcl-2 proto-oncogene on chromosome 18, and the immunoglobulin heavy chain region on chromosome 14 (JH). An additional amplification for the Ki-ras gene is performed as a control for sample DNA quality and as a reference for relative quantification. Results are reported as the ratio of amplified bcl-2 product to amplified Ki-ras product. The current specimen will be tested side-by-side with a previously stored sample, if available, to assess quantitative changes over time (trend).
This assay detects both major (mbr) and minor (mcr) fusion sequences and has an analytical sensitivity of 1 tumor cell in 100,000 normal cells.
CPT Codes:* 83891, 83896 x3, 83898 x3, 83912
Interpretive Information
Positive results indicate that the cells carry the t(14;18) translocation and are reported as a ratio between the quantities of the amplified target gene bcl-2 and the control Ki-ras gene. If there is no bcl-2 amplification (ratio = 0), the result is reported as negative. Because translocation breakpoints sometimes occur outside the areas covered in this assay, a negative result does not rule out absence of this translocation.
For monitoring MRD, we recommend monitoring changes with time (trend) rather than the absolute ratio from a single measurement.
Specimen Requirements
| Sample Type | Requested Volume | Container | Storage |
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| Whole blood | 5 mL (1 mL minimum) | EDTA (lavender top) tube | Room temperature or refrigerated |
| Bone marrow | 3 mL (0.5 mL minimum) | EDTA (lavender top) tube | Room temperature |
| Fresh tissue | RPMI Media | Room temperature or refrigerated | |
| Fresh frozen tissue | Sterile container | Frozen | |
| Formalin-fixed, paraffin-embedded tissue | Room temperature or refrigerated | ||
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* The CPT codes provided are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed.