T-cell Receptor Gamma (TRG) Clonality Detection by PCR and Capillary Electrophoresis
CPT Code(s)
81342, G0452
Synonym(s)
TCR-gamma Gene Clonality Detection, T-cell Receptor (TRG) Gamma Gene Rearrangement, TCRG
Performed
Molecular Diagnostics Laboratory
Clinical Indication and Relevance
The assay is useful to assist with the diagnosis of T-cell malignancies. The assay can also be used to detect minimal residual disease in follow-up samples.
Methodology
DNA is isolated and amplified by PCR using the Invivoscribe T-cell Receptor Gamma Gene Rearrangement Assay 2.0. Primers target the conserved regions of the variable (V) and joining (J) sequences of TRG. The gene rearrangements are detected by analyzing the PCR products by capillary gel electrophoresis. The assay sensitivity for detection of clonal T-cell populations is 10% of lymphocytes.
Minimum Specimen Requirements
Collect
- Peripheral blood (PB): 3-5 mL, in purple top (sodium EDTA) tube.
- Bone marrow (BM): 1-3 mL, drawn into a syringe containing anticoagulant and then
delivered in purple top tube (EDTA). - Fresh or frozen tissue: fresh tissue should be obtained in a sterile manner, and a minimum
3 mm3
of tissue is required. Fresh tissue should be placed in culture medium for transport
or snap frozen (see transport section below). - Formalin-fixed, paraffin-embedded (FFPE) tissue blocks: send tissue block to the lab, or
contact lab for instructions regarding cutting paraffin sections for molecular studies.
Transport
- PB or BM sample: Deliver immediately at 2-8°C (wet ice or cold packs). Do not freeze.
- Fresh tissue samples should be delivered at room temperature in RPMI culture medium within 3 hours of collection, or snap frozen in liquid nitrogen at -70°C and packed in
dry ice for delivery. Please do not allow frozen tissues to thaw. - Formalin-fixed paraffin embedded (FFPE) tissue blocks and slides can be delivered at controlled temperatures, not to exceed 30C.
Stability
PB or BM samples: ambient – 1 hour; refrigerated – 48 hours.
Turnaround time
Five to seven working days
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