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| Test Description |
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Test Name
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FISH, XY
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Synonym(s)
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XY FISH
FISH, sex chromosomes
Sex chromosomes FISH
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Description
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Fluorescence In Situ Hybridization (FISH) is performed to evaluate the number of X and Y chromosome signals present in each cell. Useful for newborns with ambiguous genitalia; for diagnosing low-level mosaicism in individuals with constitutional (congenital) sex chromosome abnormalities; or for monitoring bone marrow engraftment following opposite-sex transplants.
Note: When used to evaluate for constitutional (congenital) sex chromosome abnormalities, Cytogenetics, Blood, Constitutional Karyotype must be ordered on the same specimen (unless cytogenetic analysis has been performed on a prior specimen).
See also: FISH, SRY
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Methodology
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Dual color fluorescently labeled DNA probes for the centromeres of the X and Y chromosomes are hybridized to unstained interphase nuclei on a slide. 200 cells are scored for the number of X and Y signals.
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Performed
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Daily |
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Turnaround Time
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1-2 Days |
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Specimen Requirements
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- Bone Marrow: 2 ml aspirated bone marrow 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.
- Peripheral Blood: Minimum 3 mL aseptically collected blood in a 5 mL green top, sodium heparin tube (or 2 mL pediatric green top, sodium heparin tube). DO NOT use lithium heparin tubes.
- Tissue: At least 5mm3 of aseptically collected fresh, non-necrotic tissue, or a generous 2 mm diameter (minimum) full thickness skin biopsy. 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 cytogenetics 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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Rejection Criteria
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Frozen, clotted, hemolyzed or grossly contaminated specimens. Incorrect anticoagulant used. Frozen or fixed tissue specimens, or tissue specimens sent without tissue culture medium. |
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CPT Code(s)
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88271x2, 88275, 88291
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Reference Range
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See interpretive report |
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Contact
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Cytogenetics Lab: (214) 645-7000
Customer Service: (214) 645-7057 or Toll Free (877) 887-8136
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Last Modified: Feb 11, 2008 |
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