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HelpTest Code TCGRV T-Cell Receptor Gene Rearrangement, PCR, Varies
Reporting Name
T Cell Receptor Gene Rearrange, VUseful For
Determining whether a T-cell population is polyclonal or monoclonal using body fluid or tissue specimens
Method Name
Polymerase Chain Reaction (PCR)
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
VariesShipping Instructions
Body fluid or spinal fluid specimens must arrive within 4 days of collection.
Specimen Required
Submit only 1 of the following specimens:
Specimen Type: Body fluid
Container/Tube: Sterile container
Specimen Volume: At least 5 mL
Collection Instructions:
1. If the volume is large, pellet cells prior to sending.
2. Send less volume at ambient temperature or as a frozen cell pellet.
Specimen Stability Information:
Body fluid: Ambient 4 days/Refrigerated/Frozen
Cell pellet: Frozen
Specimen Type: Paraffin-embedded bone marrow aspirate clot
Container/Tube: Paraffin block
Specimen Stability Information: Ambient
Specimen Type: Frozen tissue
Container/Tube: Plastic container
Specimen Volume: 100 mg
Collection Instructions: Freeze tissue within 1 hour of collection.
Specimen Stability Information: Frozen
Specimen Type: Paraffin-embedded tissue
Container/Tube: Paraffin block
Specimen Stability Information: Ambient
Specimen Type: Tissue slides
Container/Tube: Unstained tissue slides
Specimen Volume: 10 slides
Specimen Stability: Ambient
Specimen Type: Spinal fluid
Container/Tube: Sterile vial
Specimen Volume: 5 to 10 mL
Specimen Stability Information: Ambient 4 days/Refrigerated
Specimen Type: Extracted DNA
Container/Tube: 1.5- to 2-mL tube with indication of volume and concentration of DNA
Specimen Volume: Entire specimen
Collection Instructions:
1. Label specimen as extracted DNA and source of specimen
2. Indicate volume and concentration of DNA on label
Specimen Stability Information: Refrigerated/Ambient
Specimen Minimum Volume
Body fluid or Spinal fluid: 1 mL
Tissue: 50 mg
Extracted DNA: 50 microliters at 20 ng/mcL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Varies | Varies | ||
Reject Due To
| Bone marrow core biopsies Paraffin shavings |
Reject |
Special Instructions
Reference Values
An interpretive report will be provided.
Positive, negative, or indeterminate for a clonal T-cell population
Day(s) Performed
Monday through Friday
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 |
|---|---|---|
| TCGRV | T Cell Receptor Gene Rearrange, V | In Process |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 19936 | Final Diagnosis: | 22637-3 |
| MP016 | Specimen: | 31208-2 |
| 608953 | Signing Pathologist | 19139-5 |
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 TCR, 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.
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 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.
Method Description
Genomic DNA is extracted from the tissue source. 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)