Laboratory Lab results are too important to go anywhere else.

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, Gene Test

Test Codes

EPIC: LAB5128, SOFT LAB: MTCLG, SOFT GENE: MTCEL, SOFTPATH: MBCLG

Department

Molecular Pathology

Specimen Collection Criteria

Collect: One of the following specimen types, as described below:

1. Blood: 5.0 mL whole blood in Lavender-top EDTA tubes. Invert several times to mix blood. (Minimum: 3.0 mL)
2. Bone Marrow: 2.0 mL bone marrow in a Lavender-top EDTA tube. Invert several times to mix bone marrow.
3. Spinal Fluid: 10 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)
4. 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.
• DNA will be assessed for quality. If it is deemed unacceptable, testing will be cancelled with client notification.
• 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 (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).

Rejection Criteria

• Anticoagulants other than EDTA or heparin.
• Clotted peripheral blood or bone marrow.
• Fresh or frozen tissue specimen.
• Decalcified tissue.
• 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

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.

In-Lab Processing

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.

Storage

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

Paraffin-Embedded Tissue
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

Laboratory

Royal Oak Clinical Molecular Pathology Laboratory

Performed

Monday – Friday.
Results available within 10 business days.

Reference Range

An interpretive report will be provided.

Test Methodology

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.

Interpretation

An interpretive report will be provided.

Clinical Utility

Detection of a prominent 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.

Limitations:

1. This test is neither 100% sensitive nor 100% specific.
2. 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.
3. 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).
4. This assay cannot determine whether a clonal rearrangement is physiologic or neoplastic.
5. This assay cannot be utilized to definitively assign lineage (i.e., B-cell vs. T-cell) to a neoplastic process.

Reference

1. 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.
2. 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.

CPT Codes

81342

Contacts

Last Updated

3/23/2021