Mayo Test Catalog, (Sorted By Test Name) - Mayo Medical ...

MBCR
80578
BAKDM
89609
BCR/ABL, Translocation 9;22, FISH (D-FISH)
Clinical Information: A proliferation of cells with a t(9;22)(q34;q11.2) occurs in the bone marrow
and peripheral blood of more than 90% of patients with chronic myeloid leukemia (CML); in
approximately 6% of children and 17% of adults with acute lymphoblastic leukemia (ALL); and
approximately 1% of patients with acute myeloid leukemia (AML) with immature granulocytes. The
abnormal chromosome 22 derived from this translocation is called the Philadelphia (Ph) chromosome.
The remaining 10% of patients with CML have a variant Ph chromosome. The classic Ph and all variants
result in fusion of part of the Abelson (ABL1) oncogene from 9q34 with the breakpoint cluster region
(BCR) at 22q11.2. Conventional cytogenetic studies are widely used to quantify disease and to monitor
the effectiveness of treatment for patients with CML; especially those on interferon or Gleevec/lmatinib
mesylate therapy. Considerable evidence shows a strong correlation between changes in percentage of
Ph-positive metaphases after therapy and response to therapy. The best outcome for survival and
prolonged chronic phase appears to be in patients with CML in whom the percentage of Ph-positive
metaphases is no longer detectable by conventional cytogenetics. When this happens, the patient is in
cytogenetic remission. This test offers a highly sensitive method using FISH and DNA probes for ABL1
and BCR for quantifying nonproliferating neoplastic cells with BCR and ABL1 fusion. D-FISH (dual)
ffusion FISH is a testing strategy that uses 2 fluorescent probes to identify and differentiate between the
classic and variant Ph chromosomes by detecting double BCR and ABL1 fusion in cells with a
t(9;22)(q34;q11.2): 1 on the abnormal chromosome 9 and 1 on the Ph chromosome.
Useful For: Establishing the percentage of neoplastic interphase nuclei for patients with chronic
myeloid leukemia (CML) at diagnosis and at all times during treatment, even in cytogenetic remission
Detecting all known forms of the Philadelphia (Ph) chromosome Identifying and monitoring of the Ph
chromosome in patients with CML, acute lymphocytic leukemia (ALL), or acute myeloid leukemia
(AML) It is recommended that conventional chromosome analysis (BM/8506 Chromosome Analysis, for
Hematologic Disorders, Bone Marrow) also be performed at initial diagnosis. Subsequently, D-FISH
alone can be used to monitor the effectiveness of therapy.
Interpretation: Specimens that contain > or =1% neoplastic nuclei with BCR and ABL1 fusion have a
high likelihood of having a clone with t(9; 22) (q34; q11.2) or a variant of this anomaly. Specimens with
1% disease when 500 interphase nuclei are scored and >0.079% disease when 6,000 nuclei are
scored. To monitor the effectiveness of therapy, it is useful to divide the percentage of neoplastic cells
after therapy by the percentage of neoplastic cells before treatment. Many clinicians use this calculation to
classify the patient's response to therapy according to the table below. Cytogenetic Response to Therapy
Percent Neoplastic Nuclei Post-treatment Relative to Pretreatment Absent 100% Minimal 67%-99%
Minor 33%-66% Major 1%-32% Complete 0%
Reference Values:
An interpretive report will be provided.
Clinical References: 1. Dewald GW, Wyatt WA, Silver RT: Atypical BCR and ABL D-FISH
patterns in chronic myeloid leukemia and their possible role in therapy. Leuk Lymphoma
1999;34(5-6):481-491 2. Dewald GW, Juneau AL, Schad CR, Tefferi A: Cytogenetic and molecular
genetic methods for diagnosis and treatment response in chronic granulocytic leukemia. Cancer Genet
Cytogenet 1997;94:59-66 3. The Italian Cooperative Study Group on Chronic Myeloid Leukemia:
Interferon alpha-2a as compared with conventional chemotherapy for the treatment of chronic myeloid
leukemia. N Engl J Med 1994;330:820-825 4. Dewald GW: Interphase FISH studies for chronic myeloid
leukemia. In Methods in Molecular Biology. Vol 204. Molecular Cytogenetics: Protocols and
Applications. Edited by YS Fan. Totowa, NJ, Humana Press, USA, 2002 pp 311-342
BCR/ABL, Tyrosine Kinase Inhibitor Resistance, Kinase Domain
Mutation Screen
Clinical Information: Chronic myeloid leukemia (CML) is characterized by the presence of the
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