CHRONIC MYELOID LEUKEMIA

 Fluorescent in situ hybridization (FISH) test is offered to identify the translocation, t(9;22)(q34;q11.2), associated with Chronic Myeloid Leukemia (CML).

 REASONS FOR REFERRAL

·        Individuals suspected of having a hematologic malignancy, specifically CML, in lieu of conventional chromosome analysis or when no metaphases are obtained for chromosome analysis

·        Testing for residual disease or treatment response in a patient with a known t(9;22)(q34;q11.2)

TESTING METHODOLOGY

·        Bone marrow or peripheral blood are cultured without mitogen for 24 to 48 hours.

·        FISH is the application of fluorescently labeled DNA probes to metaphase chromosomes or interphase nuclei for the detection of abnormalities. This assay uses dual probes that span the breakpoint regions on chromosomes 9q34 and 22q11.2. Dual fusion signals are produced when the translocation occurs. Analysis is based on fluorescent signals present in 200 or more interphase nuclei.  

SPECIMEN REQUIREMENTS

·        Minimum of 0.5 mL of bone marrow in sodium heparin or bone marrow transport media (provided upon request). This is the preferred specimen.

·        5-10 mL peripheral blood in sodium heparin only if white blood count higher than 10,000 and at least 10% immature myeloid cells.

·        A complete Cytogenetics/Biochemical Genetics Requisition Form must accompany the specimen.

·        Transport in ambient temperature. Specimen cannot be frozen.

 TURNAROUND TIME: 7 days

 CPT CODES: 88271, 88275, 88237, 88291