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Pediatric B Cell Acute Lymphoblastic Leukemia FISH Panel Fluorescence In Situ Hybridization Analysis

FISH, genetic, ALL, COG, pediatric FISH panel, SOFT GPALL, SOFT GPAL2, ETV6/RUNX1and BCR/ABL1 fusion, MLL gene rearrangement, chromosome 4, and 10 trisomies, TCF3/PBX1 gene rearrangement, PDGFRB gene rearrangement, ABL1 and ABL2 gene rearrangements, and IGH/IL3 gene rearrangement, Children's Oncology Group

Test Codes

EPIC: LAB3654

Department

Cytogenetics

Specimen Collection Criteria

Collect: Bone marrow aspirate in a Dark Green-top Sodium Heparin tube. (Minimum: 1.0 mL)

A copy of the requisition must be sent with the specimen.

Physician Office/Draw Specimen Preparation

Do not freeze specimen. Maintain specimens at room temperature (20-25°C or 68-77°F) prior to courier pickup. For delays in transport (greater than 48 from the time of collection), refrigerate (2-8°C or 36-46°F) the specimen.

Preparation for Courier Transport

Transport: Bone marrow, at room temperature (20-26°C or 68-78.8°F) or refrigerated (2-8°C or 36-46°F).

Rejection Criteria

Specimens arriving in the Laboratory 4 days or more following the original collection date.

Fixed or frozen specimens. 

In-Lab Processing

Specimens are processed immediately upon receipt in the Laboratory.

Storage

Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): 48 hours
Refrigerated (2-8°C or 36-46°F): 96 hours
Frozen (-20°C/-4°F or below): Unacceptable

Specimen Storage in Department Prior to Disposal:

Refrigerated (2-8°C or 36-46°F): 7 days. A backup cell pellet is maintained for three weeks after the case has been signed out.

Laboratory

Royal Oak Cytogenetics Laboratory

Performed

Monday – Friday, 8:00 am – 5:00 pm.
Results available within 7 days of receipt in the Laboratory.

Reference Range

Positive or negative for a neoplastic clone. An interpretative report will be provided.

Test Methodology

Fluorescence In Situ Hybridization (FISH) Analysis.

Interpretation

High hyperdiploidy defines a distinct subset characterized by a favorable prognosis.

More specifically, hyperdiploid ALL with simultaneous trisomy of chromosomes 4 and 10 have the lowest treatment failure and the best clinical outcome. The most common translocation in pediatric pre-B ALL is t(12;21)(p13;q22) which is recognized in up to 30% of childhood B-precursor ALL, but is rare or absent in infants and in adults with ALL. The t(12;21) is associated with a good prognosis. The Ph chromosome, t(9;22)(q34;q11.2) with BCR/ABL1 fusion, is observed in approximately 5% of children and is associated with a poor prognosis. Translocations of 11q23, causing rearrangements of the MLL gene, predict a clinically aggressive disease with a poor prognosis. Another recurrent translocation in ALL, the t(1;19)(q23;p13.3), is seen in approximately 5% of adult and childhood ALL and encodes the fusion protein E2A/PBX1 (TCF3/PBX1). This was previously thought to represent a poor prognostic marker, but intensification of therapy in pediatric patients has overcome its effects on outcome.

Clinical Utility

The identification of recurrent chromosomal aberrations as prognostic markers in childhood acute lymphoblastic leukemia (ALL) has had a major impact on efforts to cure this disease, and for this reason is a major component, along with immunophenotype, of the WHO classification of ALL. Approximately 80% of ALL cases demonstrate clonal chromosome abnormalities. The remaining cases either present a normal karyotype or cannot be analyzed due to a variety of factors such as poor chromosome morphology and the apoptotic tendency of ALL blasts in culture. For this reason, FISH has become an important tool for the assessment of genetic aberrations in ALL. Many clinical trials, including those established by the Children’s Oncology Group (COG), require all newly diagnosed ALLs to undergo both conventional cytogenetic testing as well as molecular cytogenetic characterization for risk-stratification utilizing a FISH panel to identify ETV6/RUNX1and BCR/ABL1 fusion; MLL gene rearrangement; chromosome 4 and 10 double trisomy and TCF/PBX1, IGH/IL-3, ABL1, ABL2, and PDGFRB gene rearrangements.

Guidelines for Cytogenetic/Molecular Follow-Up Testing of Hematopoietic Malignancy

Reference

1. Harrison CJ, Moorman AV, Barber KE, et al. (2005) Interphase molecular cytogenetic screening for chromosomal abnormalities of prognostic significance in childhood acute lymphoblastic leukemia: a UK Cancer Cytogenetics Group Study. Br J Haematol 129(4), 520-530.

CPT Codes

88271x14 (DNA probe, each), 88275x9 (Interphase analysis, 100-300 cells). 

Contacts

Last Updated

8/9/2024