Laboratory Test Information Guide

Details for Chronic Myelogenous Leukemia, by PCR

Test Name: Chronic Myelogenous Leukemia, by PCR
Alternate Name(s): CML
BCR/ABL
Philadelphia Chromosome
Laboratory: Molecular Diagnostics
Specimen Type: Bone marrow
or
2 x 4 mL K2 or K3 EDTA Lavender top Vacutainer tube
Collection Information: Blood samples must be maintained at room temperature.
Requisition: MOLECULAR DIAGNOSTICS REQUISITION
Test Schedule: As Required
Monday - Friday
0800 - 1630 h
Turnaround time from when specimen
is received in testing laboratory:
 
Routine
10 days
Stat
 
 
Reference Range: See report
Effective Date: 2010-01-13
Revised Date: 2016-04-27
Critical Value: N/A
Interpretive Comments: Chronic myelogenous leukemia is invariably associated with a cytogenetic abnormality involving a reciprocal translocation of chromosomes 9 and 22, in which the downstream portion of the abl proto oncogene on chromosome 9 is brought into close proximity to the upstream portion of the bcr gene on chromosome 22. It is possible to detect this translocation using molecular techniques, and in addition to quantify the amount of aberrant Philadelphia Chromosome copy number [1]. RNA was extracted from peripheral blood, reverse transcribed into cDNA and amplified by PCR using primers specific for the BCR gene on chr. 22 and the ABL gene on chr. 9. BCR-ABL fusion transcripts were detected by Q-RT-PCR in a Roche light cycler. The level of fusion gene transcript in the test sample is expressed as a log reduction; i.e. log10 of the ratio of chimeric BCR-ABL/normal ABL mRNA transcript seen in a panel of individuals with untreated CML as compared to the ratio seen in the patient. The value of the ratio in untreated CML (5.0)has been adjusted to obtain log10 reduction values for a series of shared samples (GLEEM 3 Trial) in line with a dozen other molecular diagnostic laboratories across Canada. A log reduction of 4 represents a 2,000-fold reduction of chimeric BCR-ABL transcript from the average value seen in untreated CML and this assay method approaches its limit of sensitivity at a log reduction of 5.

Reference

1. Hughes TP et al N.E.J.M. (2003) 349: 1423-1432
Special Processing:  
Comments: Retesting of samples received less than 3 months after initial testing need to be approved by the Laboratory Director.

For more information click on:
Molecular Diagnostic Laboratory.
Method of Analysis: Q-RT-PCR Light Cycler
Critical Information Required: Leukocyte count must be provided as well as Clinical status of patient, i.e. phase of disease and treatment in progress (Gleevac, Bone marrow transplant etc.)
Storage & Shipment: Must be received in testing laboratory within 48 hours of collection, shipped at room temperature by courier/overnight delivery.
System Codes: 
Cerner
 
 
Referred To:  

Questions? Comments? Contact Laura Gopaul