FISH, aneuploidy panel

Aneuploidy FISH
FISH, trisomy panel
Trisomy panel FISH

Fluorescence In Situ Hybridization (FISH) is performed to evaluate the number of signals for chromosomes 13, 18, 21, X and Y in each cell.  Useful as a rapid screen for aneuploidy on amniotic fluid or blood from a critically ill newborn.  Result must be confirmed by routine chromosome analysis.

Note: Routine chromosome analysis must be ordered on the same specimen.

Fluorescently labeled DNA probes specific for the centromeres of chromosomes X (DXZ1), Y (DYZ3), and 18 (D18Z1), and for chromosome bands 13q14 (RB1) and 21q22.13-q22.2 (D21S259, D21S341, D21S342) are hybridized to unstained interphase nuclei on a slide.  100 cells are scored for the number of each fluorescent signal.

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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