Imatinib Mesylate Responsive Genes, Locus Anomalies, FISH
Detecting a neoplastic clone associated with the common chromosome anomalies seen in patients with acute leukemia or other myeloid malignancies
Tracking known chromosome abnormalities in patients with myeloid malignancies thus assessing their response to therapy.
This panel is particularly useful for specimens in which standard cytogenetic analysis is unsuccessful.
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Myeloid neoplasms are primary disorders of the bone marrow cells. These malignancies encompass several entities with extremely varied clinical courses, including acute myeloid leukemias (AML), chronic myeloproliferative disorders (CMPD), and myelodysplastic syndromes. The underlying genetic mechanisms associated with these malignancies are varied and only a portion of the genetic anomalies have targeted therapies clinically available.
One group of genes, including ABL1 (Abelson murine leukemia viral oncogene homolog 1), ABL2 (Abelson murine leukemia viral oncogene homolog 2), PDGFRA (platelet-derived growth factor receptor, alpha), and PDGFRB (platelet-derived growth factor receptor, beta) can be inappropriately activated via various genetic mechanisms and result in overexpression of their tyrosine kinase activity. Tyrosine kinase activity plays an important role in cellular signaling, division, and differentiation; overexpression may cause some cancers. The myeloid malignancies associated with these aberrantly expressed genes include AML, chronic myelogenous leukemia (CML), hypereosinophilic syndrome/systemic mast cell disease (HES/SMCD), and atypical CMPD. These translocations can also be seen in lymphoid neoplasms, including acute lymphoblastic leukemia (ALL) and lymphomas, and they can also possess a varied genetic etiology. Several clinical studies have demonstrated that the malignancies displaying overexpression of these genes are responsive to imatinib mesylate (Gleevec), a drug that specifically targets these genes.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
An interpretive report will be provided.
A neoplastic clone is detected when the percent of cells with an abnormality exceeds the normal cutoff for any given probe.
The presence of a positive clone supports a diagnosis of malignancy.
The absence of an abnormal clone does not rule out the presence of neoplastic disorder.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
This test is not approved by the FDA and it is best used as an adjunct to existing clinical and pathologic information.
Each probe was independently tested and verified on unstimulated peripheral blood and bone marrow specimens. Normal cutoffs for each probe were calculated based on the results of at least 20 normal specimens. For each probe set, a series of chromosomally abnormal specimens were evaluated to confirm that each probe set detected the anomaly it was designed to detect.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
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2. Dave BJ, Wiggins M, Higgeins CM, et al: 9q34 rearrangements in BCR/ABL fusion-negative acute lymphoblastic leukemia. Cancer Genet Cytogenet 2005 Oct 1;162:30-37
3. Pardanani A, Reeder T, Porrata LF, et al: Imatinib therapy for hypereosinophilic syndrome and other eosinophilic disorders. Blood 2003 May 1;101(9):3391-3397
4. Pardanani A, Tefferi A: Imatinib targets other than bcr/abl and their clinical relevance in myeloid disorders. Blood 2004 Oct 1;104(7):1931-1939