FISH, chromosome 7 aberrations of myelodysplasia

FISH, deletions in chromosome 7
FISH, deleted 7

Fluorescence in situ hybridization (FISH) is performed to detect aberrations of chromosome 7 as seen in myelodysplastic syndrome or in acute myeloid leukemia following treatment with alkylating agents.

See also MDS FISH panel.
Note: Conventional cytogenetic analysis should be performed in addition to FISH at initial diagnosis

Dual color fluorescently labeled probes for ELN, LIMK1 and D7S613 at chromosome band 7q11.23, and D7S486 and D7S522 at chromosome band 7q31, are hybridized to unstained interphase nuclei on a slide.  200 cells are evaluated to determine whether aberrations of chromosome 7 are present.

1. Bone Marrow: 2 ml aspirated bone marrow (preferred) anticoagulated with preservative-free sodium heparin (e.g., green-top tube). DO NOT use lithium heparin. Bone marrow biopsy may be submitted if aspirate is not available – see instructions for tissue specimens below.
2. Peripheral blood: 5 - 10 ml aseptically collected blood in a green top, sodium heparin tube. DO NOT use lithium heparin tubes. Bone marrow aspirate is always the preferred specimen in cases of suspected leukemia. Blood may be substituted in cases of untreated chronic myeloid leukemia (CML) or in acute leukemias with WBCs >35,000, but the rate of abnormal clone detection is suboptimal.
3. Tissue: At least 5mm³ of aseptically collected, fresh, non-necrotic tumor or lymph node. Identify the source of the specimen and probable diagnosis. Place specimen in 10 ml of sterile tissue culture medium immediately. Do not place in formalin or other fixative. Obtain tubes of tissue culture medium from lab prior to obtaining specimen. Store unused medium frozen; defrost prior to obtaining specimen.

Note: Deliver to lab at room temperature within 24 hours. If collected over a weekend, call the laboratory to make arrangements for specimen delivery. May be refrigerated if not transported immediately. Do not freeze. Protect from heat or cold.

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