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PCR to detect a gene
rearrangement t(14;18) , Quantitative Real-Time PCR
Questdiagnostics
PCR testing can detect very small amounts of genetic material in
a biospecimen sample, such as a gene translocation t(14:18)
which produces pro-survival protein, BCL-2, in many lymphomas.
When the PCR test is negative (a good result),
it means that there may be no abnormal cells in
the blood or marrow, which might be described as a
molecular remission.
Analogy:
A standard bone marrow test is like taking a sample of a pool
with a scoop net in the dark.
The test is only conclusive if leaves are found, because the sample
may have missed leaves
floating elsewhere in the larger pool.
PCR testing is
like examining the same sample for tiny fragments of substances that exist only in leaves. Thus, a negative
finding with PCR testing provides greater
confidence that the bone marrow is clear of the abnormal cells.
The clinical significance of a molecular remission is still not clear, but achieving this kind or response has been associated
with longer duration of response among the participants in some
studies.
PCR tests are generally given after a complete
response to treatment
has been determined using CT and
a bone marrow biopsy, mainly in clinical trials.
A limitation of the test is that
it can only show the status of the compartment tested: the blood or marrow. A conversion to negative appears to be a good prognostic indicator, but not
definitively, because the test can't determine the t:14:18 status in
lymph nodes and other areas.
"The t(14;18) translocation is characteristic of B-cell
lymphomas, occurring in up to 90% of follicular
lymphomas. It is also found in 20% to 30% of diffuse large
B-cell lymphomas ..."
analytical sensitivity of 1 tumor
cell in 100,000
normal cells.
What is PCR Testing?
opa.faseb.org
PDF
"Sometimes referred to as "molecular
photocopying," PCR can characterize, analyze,
and synthesize any specific piece of DNA or RNA. ... Medical
research and clinical medicine
are profiting from PCR mainly in two areas: detection of
infectious disease organisms, and detection
of variations and mutations in genes, especially human
genes."
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