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Unit Code 83122:
T-Cell Receptor Gene Rearrangement

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Useful For

Determining whether a T-cell population is polyclonal or monoclonal

 

Identifying neoplastic cells as having T-cell differentiation

 

Monitoring for persistent neoplasm by detecting a TCR gene

rearrangement profile similar to 1 from a previous neoplastic specimen

Clinical Information

The T-cell receptor (TCR) genes (alpha, beta, delta, and gamma)

are comprised of numerous, discontinuous coding segments. As

T-cells develop, the segments are rearranged such that each mature

T-cell has a unique rearrangement profile. Other cell types usually

retain the nonrearranged gene structures. Clonal expansion of any

T-cell results in a population of cells that all contain an identical TCR

gene rearrangement profile. Reactive T-cell expansions are polyclonal,

with each clone containing relatively few cells and no 1 clone

predominating. Neoplastic clones are generally large, such that the

clonal cells are the predominant T-cells present.

 

In the appropriate clinical/pathologic setting, detection of a prominent

TCR gene rearrangement profile may be equated to the presence of

a neoplastic T-cell clone.

Reference Values

An interpretive report will be provided.

Interpretation

An interpretive report will be provided.

 

Detection of a prominent TCR gene rearrangement profile is

consistent with the presence of a neoplastic T-cell clone. However,

the interpretation of the presence or absence of a predominant

TCR gene rearrangement profile is sometimes subjective. These

results must always be interpreted in the context of other clinicopathologic

information to determine the significance of the result.

 

The detection of a clonal TCR gene rearrangement by this test alone

is not synonymous with the presence of a T-cell neoplasm.

Cautions

This test is neither 100% sensitive nor 100% specific. False-positives

are more common than false-negatives, particularly for the polymerase

chain reaction (PCR) assay. 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 Southern blot results may result from

rearrangements that have occurred in regions not detected by the probes

or rearrangements that produce fragments of similar size to the

nonrearranged fragment. In both assays false-negative results will occur

if the clonal cells have not rearranged the TCR genes being evaluated or

are present below the sensitivity level of the assay (sensitivity is quite

variable but the assays require that at least 1-5% of the nucleated cells

present be clonal).

 

The test does not provide information regarding the following:

1. The differentiation of the clonal cell population (neoplastic cells other

     than T-cells may occasionally have TCR gene rearrangements)

2. Whether a prominent clone is physiologic or neoplastic

Special Instructions and Forms

• MayoConnect Additional Test Information 

Clinical Reference

Coad JE, Olson DJ, Lander TA, McGlennen RC:  Molecular

assessment of clonality in lymphoproliferative disorders: II. T-cell

receptor gene rearrangements. Mol Diagn 1997 Mar;2(1):69-81

Key