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BCR/ABL minor t(9;22) P190 - Quantitative by Polymerase Chain Reaction

P BCR ABLm

Test Synonym:

BCR-ABL t(9;22) quantitative; Philadelphia Chromosome

Associations:

p190 protein in chronic myeloid leukemia and acute lymphoblastic leukemia

Test Synonym:

83891 – Molecular isolation
83892 – Enzymatic digestion
83894 – Separation by gel electrophoresis
83896 X2 – Nucleic acid probe
83898 X2– Amplification of patient nucleic acid, primer pair

83902– Reverse transcriptase

83912-26 – Interpretation and report

Turnaround Time:

3-5 days; specimens accepted Monday through 1:00PM on Friday. Assay run once/week

Methodology:

Quantitative reverse transcriptase Polymerase Chain Reaction (qPCR)

Specimen Requirements:

  • 10.0ml (min. 9.0ml) peripheral blood in EDTA
  • 5.0ml (min. 2.5ml) bone marrow in EDTA

    • Causes for Rejection:

  • Specimen >48 hrs. old
  • Specimen clotted
  • Specimen stored or shipped at incorrect temperature
  • Specimen in incorrect anticoagulant
  • Insufficient specimen volume

    Specimen Stability:

  • Specimen must be received by MPLN within 48 hrs. of collection
  • Stable at 2-8°C

    • Storage and Handling:

    Ship peripheral blood and bone marrow at ambient temperature (do not ship on ice or cold pack; do not ship to arrive after 1:00PM on Friday, or on weekends)

    Reference Range:

    Positive: minor BCR-ABL fusion quantified relative to ABL and to prior test result
    Negative: minor BCR-ABL fusion not detected (<0.001% BCR-ABL/ABL)

    Indication:

    The Philadelphia chromosome results from a translocation [t(9;22)(q34;q11.2)] that fuses the c-Abl proto-oncogene on chromosome 9 to the BCR (breakpoint cluster region) gene on chromosome 221. The Bcr-Abl protein exhibits enhanced tyrosine kinase activity. Inhibition of this enzymatic activity by Gleevec® is effective in the treatment of chronic myelogenous leukemia (CML)2. The BCR-ABL minor test is useful whenever CML is suspect but a negative result is obtained with the BCR-ABL major test. 1% of Ph+ CML involves the minor fusion only. In cases of Ph+ acute lymphoblastic leukemia (ALL)3, ~90% of childhood  ALL and 20-50% of adult ALL involve the minor BCR-ABL fusion. The primary clinical utilities for the StrataFLEX BCR-ABL minor and or major quantitative PCR test  include (a) the determination of a baseline level of BCR-ABL expression in newly diagnosed patients, and (b) the monitoring of patients for molecular evidence of minimal residual disease (MRD) or molecular remission in response to chemotherapy or allogeneic bone marrow transplantation3. Molecular monitoring of BCR-ABL expression should be repeated at a minimum of three-month intervals to establish the kinetics (trend) of BCR-ABL expression4.

    References:

    1. Kurzrock et al. (2003). Philadelphia chromosome-positive leukemias: from basic mechanisms to molecular therapeutics. Ann Intern Med 138:819

    2. Hughes et al. (2003). Frequency of major molecular responses to Imatinib or Interferon Alfa plus Cytarabine in newly diagnosed chronic myeloid leukemia. N Engl J Med 349(15):1423

    3. Gleissner et al. (2002). Leading prognostic relevance of the BCR-ABL translocation in adult acute B-lineage lymphoblastic leukemia: a prospective study of the German Multicenter Trial Group and confirmed polymerase chain reaction analysis. Blood 99:1536
    4. Olavarria et al. (2001). Early detection of BCR-ABL transcripts by quantitative reverse transcriptase–polymerase chain reaction predicts outcome after allogeneic stem cell transplantation for chronic myeloid leukemia. Blood 97:1560