PML/RAR? T(15;17) TRANSLOCATION BY FISH

Code
000.0000
Name
PML/RAR? T(15;17) TRANSLOCATION BY FISH
Category
None
Department
Send-Out
Start Date
Expiration Date
Synonyms
Acute Leukemia FISH
CPT Codes
88271x2; 88275
Site
SBMF
Reference Test
36150
ATLAS Test Code

Specimen Information

Type

Lavender, EDTA Whole Blood

Volume

1.0 mL

Transport Info

Room temperature

Fasting Required?
False
Patient Instructions

Reference Range

A dual color, dual fusion probe (LSI PML/RARa) was used in this method.
At least 200 interphase cells are counted.
Dual fusion pattern at or greater than 1% is considered positive for t(15;17)(q22;q21.1).

Methodology

Fluorescence in Situ Hybridization (FISH)

Clinical Significance

The current WHO classification for acute myeloid leukemia (AML) consists of 4 major categories based on a combination of morphologic, immunophenotypeic, genetic and clinical features. Specific cytogenetic abnormalities in AML are highly correlated with response to therapy and survival. Identification of these defects is thus a powerful predictor of clinical outcome, and further divides these categories into favorable, intermediate, or unfavorable prognosis groups based on the demonstration of specific chromosomal changes.
Acute promyelocytic leukemia (APL;AML-M3 in the French-American-British or FAB classification), constitutes approximately 8% of adult AML, and results in a proliferation of malignant promyelocytes in the blood and marrow, either with typical hypergranular or variant microgranular morphology. This acute leukemia characteristically demonstrates the translocation t(15;17), that fuses the promyelocytic leukemia (PML) gene on chromosome 15 to the retinoic acid receptor-alpha gene on chromosome 17 (PML/RARa), as well as a few other variants. The PML/RARa translocation conveys a unique sensitivity to treatment with all-trans-retinoic acid (ATRA) and an overall favorable clinical response to therapy, with the expectation of cure in up to two thirds of cases. While this translocation can be identified by a number of molecular methods, fluorescence in situ hybridization, or FISH, is a robust technique applicable to both peripheral blood and bone marrow specimens that does not require cell culture (as in classic cytogenetics), or tumor RNA (a less stable nucleic acid required for RT-PCR assays), and provides a relatively rapid and reliable detection system.

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