IgV_H Mutation Analysis

Clinical Use

•	Assess prognosis for patients with chronic lymphocytic leukemia (CLL)

Clinical Background
CLL is the most common leukemia in the Western world. Patients with CLL follow heterogeneous clinical courses. Some survive for prolonged periods without definitive therapy, while others die rapidly, despite aggressive treatment. CLL patients can be divided into 2 basic groups on the basis of the mutational status of the immunoglobulin heavy-chain variable-region (IgV_H) gene in leukemic cells: patients with IgV_H gene mutations have longer survival than those without. Thus, mutation analysis may be useful for planning management strategies.

Two potential surrogate markers, CD38 and ZAP-70, have been investigated because of their association with lack of IgV_H mutation, but the correlation is not 100%.

Method
Following extraction of total RNA from blood or bone marrow samples, the IgV_H gene is amplified by reverse transcription-polymerase chain reaction (RT-PCR) and sequenced by dideoxy chain termination cycle sequencing with automated base calling. The nucleotide sequences are then aligned to NCBI IgBlast. A mutated status is assigned when there is >3% deviation from germline IgV_H sequence. Sequencing may not be possible for specimens with <10% clonal B-cells.

CPT Codes:* 83891, 83894, 83902, 83901, 83904, 83912

Interpretive Information
A "mutated" result indicates >3% deviation from the germline sequence. Patients with IgV_H mutations tend to have a more favorable prognosis, with longer overall survival.

Specimen Requirements
3 mL room-temperature or refrigerated whole blood in an EDTA (lavender-top) tube; 1 mL minimum. Heparin (green-top) and ACD (yellow-top) whole blood is also acceptable.

Alternatively, submit 1 to 2 mL bone marrow.

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Online Test Information for Your Patients
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•	Leukemia
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This test was developed and its performance characteristics determined by Quest Diagnostics Nichols Institute. It has not been cleared or approved by the U.S. Food and Drug Administration. The FDA has determined that such clearance or approval is not necessary. Performance characteristics refer to the analytical performance of the test.

* The CPT codes provided are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed.

Polymerase chain reaction (PCR) is performed pursuant to a license agreement with Roche Molecular Systems, Inc.

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