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HelpMayo Test ID TCGBM T-Cell Receptor Gene Rearrangement, PCR, Bone Marrow
Shipping Instructions
Specimen must arrive within 7 days of collection.
Necessary Information
Include relevant clinical information and cytogenetics results, if available.
Specimen Required
Container/Tube:
Preferred: Lavender top (EDTA)
Acceptable: Yellow top (ACD)
Specimen Volume: 2 mL
Collection Instructions:
1. Invert several times to mix bone marrow.
2. Send bone marrow specimen in original tube. Do not aliquot.
Useful For
Determining whether a T-cell population is polyclonal or monoclonal
Testing Algorithm
For information see:
-Bone Marrow Staging for Known or Suspected Malignant Lymphoma Algorithm
Special Instructions
Method Name
Polymerase Chain Reaction (PCR)
Reporting Name
T Cell Receptor Gene Rearrange, BMSpecimen Type
Bone MarrowSpecimen Minimum Volume
1 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Bone Marrow | Ambient (preferred) | 7 days | |
| Refrigerated | 7 days |
Reject Due To
| Gross hemolysis | Reject |
| Moderately to severely clotted | Reject |
Clinical Information
The T-cell receptor (TCR) genes (alpha, beta, delta, and gamma) are comprised of numerous, discontinuous coding segments that somatically rearrange to produce heterodimeric T-cell surface receptors, either alpha/beta (90%-95% of T cells) or gamma/delta (5%-10% of T cells). With rare exceptions (eg, some neoplastic B-lymphoid proliferations), other cell types retain the germline configuration of the TCR genes without rearrangement.
The marked diversity of somatic TCR-gene rearrangements is important for normal immune functions but also serves as a valuable marker to distinguish abnormal T-cell proliferations from reactive processes. A monoclonal expansion of a T-cell population will result in the predominance of a single TCR-gene rearrangement pattern. In contrast, reactive T-cell expansions are polyclonal (or multiclonal), with no single clonotypic population predominating in the population of T cells. These distributive differences in both TCR sequence and genomic rearrangement fragment sizes can be detected by molecular techniques (ie, polymerase chain reaction) and used to determine if a population of T cells shows monoclonal or polyclonal features.
Reference Values
An interpretive report will be provided.
Positive, negative, or indeterminate for a clonal T-cell population
Interpretation
An interpretive report will be provided.
Results will be characterized as positive, negative, or indeterminate for a clonal T-cell population.
In the appropriate clinicopathologic setting, a monoclonal result is associated with a neoplastic proliferation of T cells (see Cautions).
Cautions
To determine the significance of the result, it must always be interpreted in the context of other clinicopathologic information.
The interpretation of the presence or absence of a predominant T cell receptor (TCR)-gene rearrangement profile is sometimes subjective.
The detection of a clonal TCR-gene rearrangement by this test is not necessarily synonymous with the presence of a T-cell neoplasm. False-positive results can occur because of the sensitivity of polymerase chain reaction (PCR) technique and the problem of nonuniform (skewed) amplification of target T-cell gene rearrangements. The latter problem can occur when the total T-cell number in a sample is limited or due to physiologic skewing of the T-cell repertoire, as seen with aging, posttransplantation, or T-cell reactions in autoimmune or (nonlymphoid) malignancies. False-negative results can occur for many reasons, including tissue sampling, poor amplification, or failure to detect a small minority of T-cell gene segment rearrangements with the use of consensus PCR primers. In some cases, an indeterminate or equivocal result will occur because the pattern of gene rearrangements is abnormal (compared to typical polyclonal T-cell processes), but not definitive, for a monoclonal T-cell population. In these situations, distinction of a small monoclonal subpopulation from an overrepresented, but reactive, population may not be possible.
Clinical Reference
1. Liu H, Bench AJ, Bacon CM, et al. A practical strategy for the routine use of BIOMED-2 PCR assays for detection of B- and T-cell clonality in diagnostic haematopathology. Br J Haematol. 2007;138(1):31-43
2. van Krieken JHJM, Langerak AW, Macintyre EA, et al. Improved reliability of lymphoma diagnostics via PCR-based clonality testing: report of the BIOMED-2 Concerted Action BHM4-CT98-3936. Leukemia. 2007;21(2):201-206
3. Bruggermann M, White H, Gaulard P, et al. Powerful strategy for polymerase chain reaction-based clonality assessment in T-cell malignancies Report of the BIOMED-2 Concerted Action BHM4 CT98-3936. Leukemia. 2007;21(2):215-221
4. Langerak AW, Groenen PJTA, Bruggemann M, et al. EuroClonality/BIOMED-2 guidelines for interpretation and reporting of Ig/TCR clonality testing in suspected lymphoproliferations. Leukemia. 2012;26(10):2159-2171. doi:10.1038/leu.2012.246
5. Davies K, Staniforth J, Haowei Xie W, et al. Advances in the assessment of T-cell clonality. Diag Histopathol. 2020;26(9):388-397
Method Description
Genomic DNA is extracted from the bone marrow. T-cell receptor beta (TCRB) and T-cell receptor gamma (TCRG) loci (official designations TRB and TRG, respectfully) are amplified by polymerase chain reaction (PCR) using a multiplex primer method based on the BIOMED-2 strategy. Specific primers are labeled with fluorochrome dyes, permitting precise fragment sizing of PCR products by capillary gel electrophoresis using a genetic analyzer. Each amplified locus is assessed for gene rearrangement patterns and an overall interpretation of the assay is made with regards to the presence or absence of a monoclonal population.(Unpublished Mayo method)
Day(s) Performed
Monday through Friday
Report Available
5 to 10 daysSpecimen Retention Time
Bone marrow: 2 weeks; Extracted DNA: 3 monthsPerforming Laboratory
Mayo Clinic Laboratories in Rochester
Test Classification
This test was developed using an analyte specific reagent. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
81340-TCB (T cell antigen receptor, beta) (eg, leukemia and lymphoma), gene rearrangement analysis to detect abnormal clonal population(s); using amplification methodology (eg, PCR)
81342-TCG (T cell receptor, gamma) (eg, leukemia and lymphoma), gene rearrangement analysis, evaluation to detect abnormal clonal population(s)
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| TCGBM | T Cell Receptor Gene Rearrange, BM | In Process |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 19957 | Final Diagnosis: | 22637-3 |
| 608952 | Signing Pathologist | 19139-5 |