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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