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Chronic Myelogenous Leukemia

Diagnosing and monitoring Chronic Myelogenous Leukemia (CML) is challenging. Versiti can simplify and streamline the diagnostic process for you. The experience of our Diagnostic Laboratories team, and our desire to provide you with industry-leading service, enable us to go beyond simply providing a test result.

Chronic Myelogenous Leukemia

  • Overview

    When it comes to diagnosing and treating patients with Chronic Myelogenous Leukemia (CML), precise and sensitive testing is essential. Versiti offers quantitative testing for the bcr-abl chimeric gene as well as breakpoint analysis and kinase domain mutation testing.

     The Philadelphia (Ph) chromosome is a specific abnormality found in approximately 95% of CML patients, 2-10% of pediatric ALL patients, and 20-50% of adult ALL patients. The Ph chromosome is a truncated derivative of chromosome 22 which arises through a reciprocal translocation between the long arms of chromosomes 9 and 22. A chimeric gene, bcr-abl, is generated and the upstream region of the bcr gene (normally found on chromosome 22) becomes fused to the abl gene (normally found on chromosome 9). The chimeric bcr-abl gene is transcribed in Ph-positive cells and its translated protein products, an abnormal tyrosine kinase, is the source of malignant transformation.

  • Approach

    Versiti assists health care providers in diagnosing and monitoring Chronic Myelogenous Leukemia (CML). Our experienced Diagnostic Laboratories team offers quantitative testing for the bcr-abl chimeric gene, as well as breakpoint analysis and kinase domain mutation testing. We also provide expert consultation and test interpretation to help you diagnose and determine the appropriate treatment for your patient.
    These findings illustrate the type of in-depth testing Versiti provides, along with guidance as you request specific testing.
    Molecular detection of Philadelphia chromosome-positive cells by real-time PCR is faster and significantly more sensitive than cytogenetics or FISH. It is estimated that nearly 50% of cytogenetically Ph-negative CML cases are positive by DNA analysis.
    Selective gene amplification using PCR enables the sensitive detection of the chimeric bcr-abl oncogene messenger RNA transcript unique to Ph-positive cells. Using real-time RT-PCR with fluorescent hybridization probes, it is possible for us to detect 1 Ph chromosome-positive cell within a background of 105- 106 normal cells.
    Assignment of the bcr-abl translocation (breakpoint identification) is made using electrophosresis. This test may be ordered on a sample found to be positive in the quantitative analysis.
    A significant number of patients on imatinab therapy develop resistance to the drug. Resistance can be caused by a number of mechanisms but mutations in the BCR-ABL kinase domain (KD) are frequently observed in patients with late stage disease, resistance to therapy and loss of therapeutic response. Identification of KD mutations can assist physicians with developing an appropriate therapeutic strategy for their patients by indicating whether a higher dose of imatinib, use of dasatinib or nilotinib or other therapies might be more beneficial. If KD mutations are not present, testing for other mechanisms of resistance can be considered.
    Patients should be considered for kinase domain mutation testing if they are:

    • Patients presenting in advanced-phase disease
    • Chronic phase patients with an inadequate response or loss of response to tyrosine kinase inhibitors
    • Patients who have a rise in BCR-ABL levels of at least 5-fold that has been confirmed by more than one test

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