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Test Name:
CHIC2, 4q12 Deletion (FIP1L1 and PRGFRa Fusion), by FISH

• SBMF No:
  42291
• Performance Lab Name:
  Mayo Medical Laboratories
• Test Mnemonic:
  FCHIC2
• ABN:
  Required – Not FDA-Approved
• CPT Code:
  88271x3; 88275x2; 88291
• LOINC Code:
  19146-0
• Ref Lab Test No:
  84308
• Also Known As:
  CHIC2 deletion
  Eosinophilia
  FIP1L1 gene
  FIP1L1-PDGFRA kinase
  HES
  Hypereosinophilia
  Mast cell disease
  Mastocytosis
  MPD
  Myeloproliferative disorder
  PDGFRA gene
  SMCD
  Systemic mast cell disease
• Spec Type:
  Whole blood
• Spec Container:
  Green top (sodium heparin) tube(s)
• Alt Spec Type:
  Bone marrow
• Alt Spec Container:
  Green top (sodium heparin) tube
• Pref Vol:
  Whole blood: 10.0 mL
  Bone marrow: 2.0 mL
• Min Vol:
  Whole blood: 2.0 mL
  Bone marrow: 1.0 mL
• Fasting:
  No
• Patient Prep:
  Counseling and informed consent are recommended for genetic testing
  Forms required:
  Informed Consent for DNA Testing
  MayoConnect Additional Test Information
• Spec Collect:
  Whole blood: Routine venipuncture
  Bone marrow: Collected by physician
• Spec Process:
  Gently invert tube to mix blood or bone marrow with the anticoagulant
  Do not centrifuge
  Do not remove plasma from cells
  Forward entire tube of unprocessed whole blood or bone marrow to the laboratory
• Spec Store Transport:
  Room temperature
• Spec Reject:
  Clotted, frozen, or hemolyzed sample
• Spec Remarks:
  Please provide a reason for referral with each specimen. The laboratory will not reject testing if this information is not provided, but appropriate testing and interpretation may be compromised or delayed.
• Methodology:
  Fluorescence in Situ Hybridization (FISH)
• Use:
  Providing diagnostic genetic information for patients with HES and SMCD involving CHIC2 deletion
  Establishing the percentage of neoplastic interphase nuclei for patients with HES and SMCD at diagnosis and during treatment
  Monitoring response to therapy
• Clinical Significance:
  

  Imatinib mesylate (Gleevec), a small molecule tyrosine kinase inhibitor from the 2-phenylaminopyrimidine class of compounds, has shown activity in the treatment of malignancies that are associated with the constitutive activation of a specific subgroup of tyrosine kinases. A novel tyrosine kinase, generated from fusion of the Fip1-like 1 (FIP1L1) gene to the PDGFRA gene, was identified in 9 of 16 patients (56%) with hypereosinophilic syndrome (HES). This fusion results from an approximate 800 kb interstitial chromosomal deletion that includes the cysteine-rich hydrophobic domain 2 (CHIC2) locus at 4q12. FIP1L1-PDGFRA is a constitutively activated tyrosine kinase that transforms hematopoietic cells, and is a therapeutic target for imatinib in a subset of HES patients.

  Mast cell disease (MCD) is a clinically heterogeneous disorder wherein accumulation of mast cells (MC) may be limited to the skin (cutaneous mastocytosis) or involve 1 or more extra-cutaneous organs (systemic MCD [SMCD]). SMCD is often associated with eosinophilia (SMCD-eos). Mayo Medical Laboratories recently tested the therapeutic activity of imatinib in 12 adults with SMCD-eos. In this study, they demonstrated that FIP1L1-PDGFRA is the therapeutic target of imatinib in the specific subset of patients with SMCD-eos. Furthermore, they provided evidence that the CHIC2 deletion is a surrogate marker for the FIP1L1-PDGFRA fusion.

• Reference Range:
  An interpretive report will be provided

  Interpretation
  A neoplastic clone is detected when the percent of cells with an abnormality exceeds the normal reference range.

  Detection of an abnormal clone is usually associated with hypereosinophilic syndrome or systemic mastocytosis associated with eosinophilia.

  The absence of an abnormal clone does not rule out the presence of neoplastic disorder.

  Cautions
  This test does not rule out cytogenetic or molecular genetic anomalies other than those specifically associated with CHIC2 deletion or insertional translocation.

  Clinical Reference
  1. Pardanani A, Ketterling RP, Brockman SR, et al: CHIC2 deletion, a surrogate for FIP1L1-PDGFRA fusion, occurs in systemic mastocytosis associated with eosinophilia and predicts response to imatinib mesylate therapy. Blood Nov 1 2003;102(9):3093-3096

  2. Pardanani A, Brockman SR, Paternoster SF, et al: F1P1L1-PDGFRA fusion: prevalence and clinicopathologic correlates in 89 consecutive patients with moderate to severe eosiniphilia. Blood 2004;104:3038-3045

  3. Cools J, DeAngelo DJ, Gotlib J, et al: A tyrosine kinase created by fusion of the PDGFRA and FIP1L1 genes as a therapeutic target of imatinib in idiopathic hypereosinophilic syndrome. N Engl J Med Mar 2003;348(13):1201-1214

• Additional Test Info:
  Analyte Specific Reagent
  This test was developed and its performance characteristics determined by Laboratory Medicine and Pathology, Mayo Clinic. This test has not been cleared or approved by the U.S. Food and Drug Administration.
• Day Run:
  Sun-Sat (daily)
• Time Run:
  Varies
• Time Reported:
  Within 8 days
• Test Type:
  GENETIC