Molecular Test Detection

Test : Gene Rearrangement for Leukemia and Lymphoma


Indications : Gene rearrangement analysis may be ordered along with histopathology tests for the diagnosis of lymphoid leukemia and lymphomas.

Tests can be carried out on whole blood (>4ml) or bone marrow (>1ml) that are stored in PAX RNA tubes after collection.

DNA is isolated from the sample through standard methods and it is subjected to the southern blotting technique in the following manner:

• DNA is digested using a restriction enzyme and is separated according to its molecular weight on an agarose gel electrophoresis

• Incubation with Na OH helps the DNA to denature into single strands

• Separated DNA is transferred to a special blotting paper (membrane)

• This blot is incubated with many copies of single stranded DNA probes. The probes are easily detected as they are radioactive and can be exposed on an X-ray film directly, or has an attached enzyme which converts to a colored product upon incubation with a colorless substrate.

Physiology : It has been found that the immunoglobulin gene or the gene for T cell receptor is rearranged in patients with lymphoma or leukemia. Almost all T-cell and B-cell lymphomas have rearrangement in their antigen receptor genes and this has provided enough reason for it to be considered as a diagnostic test for blood related malignancies.

Normal Range : Determining whether T or B cell gene rearrangments exist in lymphod neoplasms.

Interpretation : Normal

No gene rearrangement seen in the lymphoid cells

Abnormal

Tumor cells with a single pattern of Ig or T-Cell Receptor gene rearrangement is seen. This suggests a monoclonal origin in these tumors. However, it is also important to keep in mind that clonality in lymphocytes does not indicate malignancy as it is also seen in benign and reactive conditions.

Sample : No unique rearrangment of T and B cell receptors is found.

Test Method : Southern blotting technique.

Related Tests : whole blood

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