Sorted By Test Name - Mayo Medical Laboratories

CHXP
82494
Clinical Information: 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). We recently tested the therapeutic activity of
imatinib in 12 adults with SMCD-eos. In this study, we demonstrated that FIP1L1-PDGFRA is the
therapeutic target of imatinib in the specific subset of patients with SMCD-eos. Furthermore, we provided
evidence that the CHIC2 deletion is a surrogate marker for the FIP1L1-PDGFRA fusion.
Useful For: Providing diagnostic genetic information for patients with hypereosinophilic syndrome
(HES) and systemic mast cell disease (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
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.
Reference Values:
An interpretive report will be provided.
Clinical References: 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
Chick Pea, IgE
Clinical Information: Clinical manifestations of immediate hypersensitivity (allergic) diseases are
caused by the release of proinflammatory mediators (histamine, leukotrienes, and prostaglandins) from
immunoglobulin E (IgE)-sensitized effector cells (mast cells and basophils) when cell-bound IgE
antibodies interact with allergen. In vitro serum testing for IgE antibodies provides an indication of the
immune response to allergen(s) that may be associated with allergic disease. The allergens chosen for
testing often depend upon the age of the patient, history of allergen exposure, season of the year, and
clinical manifestations. In individuals predisposed to develop allergic disease(s), the sequence of
sensitization and clinical manifestations proceed as follows: eczema and respiratory disease (rhinitis and
bronchospasm) in infants and children less than 5 years due to food sensitivity (milk, egg, soy, and wheat
proteins) followed by respiratory disease (rhinitis and asthma) in older children and adults due to
sensitivity to inhalant allergens (dust mite, mold, and pollen inhalants).
Useful For: Testing for IgE antibodies may be useful to establish the diagnosis of an allergic disease
and to define the allergens responsible for eliciting signs and symptoms. Testing also may be useful to
identify allergens which may be responsible for allergic disease and/or anaphylactic episode, to confirm
sensitization to particular allergens prior to beginning immunotherapy, and to investigate the specificity of
allergic reactions to insect venom allergens, drugs, or chemical allergens.
Interpretation: Detection of IgE antibodies in serum (Class 1 or greater) indicates an increased
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