T Cell Gene Rearrangement by PCR
Gene Rearrangement, T-cell Gene Rearrangement, T-cell gamma Gene Rearrangement, T-cell Receptor, T-cell PCR, Lymphocyte Gene Rearrangement
EPIC: LAB5128, Beaker: MTCLG
Specimen Collection Criteria
Collect: One of the following specimen types, as described below:
- Blood: 5.0 mL whole blood in Lavender-top EDTA tubes. Invert several times to mix blood. (Minimum: 3.0 mL)
- Bone Marrow: 2.0 mL bone marrow in a Lavender-top EDTA tube. Invert several times to mix bone marrow.
- Spinal Fluid: 10.0 mL spinal fluid in the original sterile collection container. An attempt will be made to extract sufficient DNA from any volume submitted. (Minimum: 5.0 mL)
- Solid Tissue:
- Paraffin-Embedded Tissue: A paraffin block must be submitted. (Slides or paraffin shavings are not acceptable.) Submit a 10% formalin-fixed, paraffin-embedded block with corresponding H&E slide. Average tissue size: 5.0 mm2.
- All specimens types should be sent to the Laboratory immediately for processing.
- The specimen must be accompanied by a completed requisition and must contain the patient name, hospital and visit number, date of birth, collection date, ordering physician, and source of specimen.
Physician Office/Draw Specimen Preparation
Maintain whole blood, bone marrow, and spinal fluid at room temperature (20-26°C or 68-78.8°F) or refrigerated (preferred) (2-8°C or 36-46°F) prior to transport. Maintain paraffin-embedded tissue at room temperature (20-26°C or 68-78.8°F).
Preparation for Courier Transport
Transport: Paraffin-embedded tissue at room temperature (20-26°C or 68-78.8°F); blood, bone marrow, or spinal fluid, refrigerated (2-8°C or 36-46°F).
- Anticoagulants other than EDTA or heparin.
- Clotted peripheral blood or bone marrow.
- Fresh or frozen tissue specimen.
- Tissue decalcified in agents other than Mol Decal (EDTA).
- Fixatives other than 10% neutral buffered formalin (e.g., zinc formalin).
- Improper labeling or inadequate information.
- Less than 10 percent tumor cellularity, at discretion of medical director.
- Poor quality and/or quantity of extracted genomic DNA.
Clients will be notified of any cancellations of testing.
Inpatient Specimen Preparation
Specimens at Royal Oak may be sent to the Surgical Pathology tube station, #201. In-house specimens are also picked up by a Surgical Pathology assistant every hour on the hour.
Maintain whole blood, bone marrow, and spinal fluid refrigerated (2-8°C or 36-46°F), or paraffin-embedded tissue at room temperature (20-26°C or 68-78.8°F) until testing.
Specimen Stability for Testing:
Blood, Bone Marrow, and Spinal Fluid
Room Temperature (20-26°C or 68-78.8°F): 72 hours
Refrigerated (2-8°C or 36-46°F): 72 hours
Frozen (-20°C/-4°F or below): Unacceptable
Room Temperature (20-26°C or 68-78.8°F): Indefinitely
Refrigerated (2-8°C or 36-46°F): Unacceptable
Frozen (-20°C/-4°F or below): Unacceptable
Specimen Storage in Department Prior to Disposal:
Room Temperature (20-26°C or 68-78.8°F): 7 days
Specimen Storage (DNA post testing):
Frozen (-25 to -15°C): 2 months
Royal Oak Molecular Pathology Laboratory
Monday – Friday.
Results available within 10 business days.
Negative for a monoclonal T-cell receptor rearrangement.
Following extraction, genomic DNA is amplified via multiplex Polymerase Chain Reaction (PCR) using primers specific for the TCR-gamma gene. Analysis is performed via automated capillary electrophoresis, followed by pathologist interpretation.
An interpretive report will be provided.
Detection of a prominent (monoclonal) TCR-gamma gene rearrangement is supportive of a neoplastic T-cell process. However, the results must always be interpreted in the context of other clinicopathologic information as non-neoplastic conditions (e.g., infectious and autoimmune processes) may yield a monoclonal TCR-gamma gene rearrangement.
- This test is neither 100% sensitive nor 100% specific.
- False-positive results are not uncommon encountered with polymerase chain reaction (PCR)-based assays. This is usually because the kinetics of end point, competitive PCR are such that the true proportions of rearrangements present may not be maintained during amplification.
- False-negative PCR results may occur if there is failure of primer binding or if the rearrangement involves a segment that is not bound by the primers used in the assay. False-negative results will also occur if the clonal cells have not rearranged the TCR-gamma genes being evaluated or are present below the sensitivity of the assay (approximately 1-5% of abnormal nucleated cells).
- This assay cannot determine whether a clonal rearrangement is physiologic or neoplastic.
- This assay cannot be utilized to definitively assign lineage (i.e., B-cell vs. T-cell) to a neoplastic process.
- Vega F, et al. A Novel Four-Color PCR Assay to Assess T-Cell Receptor Gamma Gene Rearrangements in Lymphoproliferative Lesions. Am J Clin Pathol 2001:116:17-24.
- Coad JE, et al. Molecular Assessment of Clonality in Lymphoproliferative Disorders: II. T-cell Receptor Gene Rearrangements. Mol Diagnosis 1997 Mar;2(1):69-81.
Molecular Pathology Lab – RO
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