FISH, CML/ALL, bcr/abl, Translocation 9;22

Test Code

12070

CPT Codes
88271 (x2), 88275

Preferred Specimen

5 mL whole blood or 3 mL bone marrow collected in a sodium heparin (green-top) tube

Minimum Volume

3 mL whole blood • 1 mL bone marrow

Other Acceptable Specimens

Sodium heparin (royal blue-top) tube • Sodium heparin lead-free (tan-top) tube • EDTA (lavender-top) tube

Instructions

Clinical history and reason for referral are required with test order. Prior therapy and bone marrow transplant history should be provided with test order.

Specimen viability decreases during transit. Send specimen to testing laboratory for viability determination. Do not freeze. Do not reject.

Note: If results are not possible, the test order may be canceled and replaced by a "Cytogenetics Communication".

Transport Temperature

Room temperature

Specimen Stability

Room temperature: See Instructions
Refrigerated: See Instructions
Frozen: See Instructions

Methodology
Fluorescence in situ Hybridization (FISH)

FDA Status
This test was developed and its analytical performance characteristics have been determined by Quest Diagnostics. It has not been cleared or approved by the U.S. Food and Drug Administration. This assay has been validated pursuant to the CLIA regulations and is used for clinical purposes.

Setup Schedule

Monday-Sunday Morning Report available: 5 Days

Reference Range

See Laboratory Report

Clinical Significance

This test uses fluorescence in situ hybridization (FISH) to detect molecular rearrangement of the BCR and ABL1 genes involved in translocation t(9;22). This translocation, resulting in an abnormally short chromosome 22 known as the Philadelphia chromosome (Ph), is associated with chronic myelogenous leukemia (CML), de novo acute myeloid leukemia, and acute lymphocytic leukemia (ALL) [1-3]. This test may also be used in the evaluation of Ph-negative CML and complex gene rearrangements [4].

CML is defined as a myeloproliferative neoplasm with the presence of Ph. When blood and bone marrow morphology findings suggest CML, the diagnosis is confirmed by identifying Ph using chromosome analysis and/or by detecting the BCR-ABL1 fusion gene with PCR or FISH. In 5% to10% of CML patients who have complex translocations involving chromosomes 9, 22, and other chromosome(s), Ph cannot be identified by chromosome analysis. In these patients, FISH is especially useful for detecting BCR/ABL1 rearrangement [4]. Ph is also present in some adults (~25%) and children (2%-4%) with ALL [2]. This test can be used to identify ALL with the t(9;22) BCR/ABL1 rearrangement (Ph-positive ALL).

FISH can be performed on bone marrow specimens and/or on peripheral blood. When bone marrow evaluation is not feasible, FISH on a peripheral blood specimen can be used to confirm the diagnosis of CML. The dual-fusion FISH assay used in this test has a low false-positive rate and can detect all variant translocations of Ph. However, this test is not quantitative and has not been adequately studied to confirm utility in monitoring response to treatment. qPCR is the most sensitive assay for measurement of BCR-ABL1 mRNA [1].

The results of this test should be interpreted in the context of pertinent clinical and family history and physical examination findings.

References
1. NCCN clinical practice guidelines in oncology: Chronic myeloid leukemia, Version 1.2022. National Comprehensive Cancer Network. Accessed November 9, 2021. https://www.nccn.org/
2. NCCN clinical practice guidelines in oncology: Acute lymphoblastic leukemia, Version 2.2021. National Comprehensive Cancer Network. Accessed November 9, 2021. https://www.nccn.org/
3. Arber DA, et al. Blood. 2016;127(20):2391-2405.
4. Albano F, et al. Mol Cancer. 2010;9:120.

The CPT Codes provided in this document 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. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.