Microdeletion Syndromes, FISH

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  • Microdeletion Syndrome Analysis, Fluorescence in situ Hybridization (FISH)

Special Instructions

Pertinent clinical diagnosis, previous cytogenetic studies, and probe of interest should be included with the specimen.

Expected Turnaround Time

4 - 7 days

Specimen Requirements


Fixed-cell pellet from a cytogenetic analysis, slides with metaphases and/or interphase nuclei for each probe indicated, blood, bone marrow, amniotic fluid, chorionic villi/products of conception or slides from buccal smears


Fixed-cell pellet, three slides, 10 mL blood (adult), 5 mL blood (pediatric), 3 mL bone marrow, or 10 mL amniotic fluid

Minimum Volume

Fixed-cell pellet from a cytogenetic analysis, two slides, 5 mL blood (adult), 1 mL blood (pediatric), 1 mL bone marrow, or 5 mL amniotic fluid


All blood or bone marrow in sodium heparin tube (pediatric Vacutainer® is optimal), confluent T-25 flask (amniotic fluid)


When buccal smears are used to make slides, follow these instructions:

• Have the patient rinse the oral cavity twice with drinking water.

• Scrape the inside of the oral cavity well using only one side of the premoistened applicator. A cotton swab can be used if an applicator is not available. Discard first scraping and repeat with slightly more pressure.

• Smear the collected specimen gently and evenly across a prelabeled glass slide.

• Allow the slide to air-dry at room temperature for 10 to 30 minutes. Check the quality of the slide with phase microscopy, if available, before proceeding. A good slide has 30−100 cells/lpf and appropriate morphology (ie, lying flat, no residue or film, not refractile, gray in color).

• Dip the slide(s) in a Coplin jar with 50% methanol/50% acetic acid for ten minutes (or spray with a cytology spray) and air-dry.

Storage Instructions

Maintain specimens at room temperature.

Causes for Rejection

Broken or dirty slides; excessive cellular debris; stains on slides

Test Details


Confirmation/identification of deletions below the resolution of cytogenetics (Call 800-345-4363 for list of available probes.).


Fluorescence in situ hybridization (FISH)


Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
510770 FISH Microdeletion 510771 Specimen Type 31208-2
510770 FISH Microdeletion 510772 Cells Counted 62361-1
510770 FISH Microdeletion 510773 Cells Analyzed 62360-3
510770 FISH Microdeletion 510774 FISH Result 49028-4
510770 FISH Microdeletion 510775 Interpretation 50020-7
510770 FISH Microdeletion 510777 Director Review: 48672-0
510770 FISH Microdeletion 512123 PDF 51967-8

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