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Test Code LABCOFISHCUST CONSTITUTIONAL CYTOGENETICS, FISH, CUSTOM

Specimen and Container/Tube

Whole blood

Specimen Stability

Peripheral blood: Stable at room temperature up to 24 hours after collection.

Specimen Handling and Transport Instructions

UCMC Onsite Instructions
Peripheral blood can be tubed directly to Cytogenetics via tube station #345

UCMC Offsite and UC MedLab Outreach Instructions
Deliver sample to Hyde Park according to routine transport methods.

Rejection Criteria

Specimens received in the laboratory >48 hours after collection; samples in incorrect anticoagulant, clotted, or hemolyzed

Reference Values

Results reported with current recommendations of the International Standing Committee on Human Cytogenomic Nomenclature (ISCN).

Clinical Indications

Custom FISH is indicated for familial testing following an abnormal result detected by SNP array or karyotype.

Test Components

Tissue culture
cell harvest
slide preparation
FISH analysis
interpretive report

CPT Codes

88271
88275

Methodology

Fluorescence in situ hybridization (FISH)

Additional Information

Limitations: Custom FISH will not detect sequence changes, it may not detect low levels of mosaicism, and it will not provide information for chromosomes or loci other than those targeted by the probes.

Last Review Date

4/17/2025

Ordering Notes

This test requires information regarding proband genetic test results. Prior to ordering, please provide information required and confirm whether testing is appropriate by email to:
#UCM-Cytogenetics-Lab, or CytogeneticsLab@uchicagomedicine.org

Volume

Preferred: 3mL in NaHep (dark green top vacutainer)
Minimum: 1 mL in NaHep

Turnaround Time

up to 28 days

Please note: Turnaround times can vary based on lab staffing and time required to purchase custom probes. For urgent needs and requests to expedite testing, please email #UCM-Cytogenetics-Lab, or CytogeneticsLab@uchicagomedicine.org

Synonyms/Key Search Words

FISH