Test ID TCGR T-Cell Receptor Gene Rearrangement, PCR, Blood
Useful For
Determining whether a T-cell population is polyclonal or monoclonal
Special Instructions
Method Name
DNA Extracted for Analysis/Polymerase Chain Reaction (PCR)
(PCR is utilized pursuant to a license agreement with Roche Molecular Systems, Inc. and InVivoScribe Technologies)
Reporting Name
T Cell Receptor Gene Rearrange, BSpecimen Type
Whole bloodSpecimen must arrive within 168 hours of draw.
Container/Tube:
Preferred: Lavender top (EDTA)
Acceptable: ACD
Specimen Volume: 4 mL
Collection Instructions:
1. Invert several times to mix blood.
2. Send specimen in original tube.
Additional Information: Include relevant clinical information and cytogenetics results, if available.
Forms:
1. Hematopathology Patient Information Sheet (Supply T676) in Special Instructions
2. If not ordering electronically, complete, print, and send a Hematopathology/Cytogenetics Test Request Form (T726) with the specimen
(http://www.mayomedicallaboratories.com/it-mmfiles/hematopathology-request-form.pdf)
Specimen Minimum Volume
1 mL
Specimen Stability Information
Specimen Type | Temperature | Time |
---|---|---|
Whole blood | Ambient (preferred) | 7 days |
Refrigerated | 7 days |
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 cell surface T-cell 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, PCR) 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
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 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 because of 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 over-represented, but reactive, population may not be possible.
Day(s) Performed
Monday through Friday
Report Available
5 daysPerforming Laboratory

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 U.S. 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)