FISH Study: X/Y Interphase (Sex Chromosome Constitution)

Additional Information:

UFHPL Test #: 30285

UFHPL Epic order code: LAB5851

CPT Code(s):

  • 88271x 2
  • 88273
  • 88275
  • 88291

Specimen Requirements:

  • Peripheral Blood: Collect blood aseptically in sodium heparin tubes (usually green-top tubes) and immediately rotate thoroughly to prevent clotting. For infants, obtain approximately 2 cc, and for children and adults, obtain 5 – 7 cc.
  • Skin biopsy or Other Tissues: In an aseptic manner, obtain approximately 2 mm x 2 mm, which is deep enough to ensure that the dermal layer is included. Deposit the specimen in a sterile container containing tissue culture medium with antibiotics which has been brought to room temperature prior to collection.* Alternate solid tissue samples include autopsy specimens (i.e., lung, cartilage, etc.).

Note: A separate blood sample is required if a concurrent CGH microarray study is desired.

Do not freeze or fix samples in any manner contrary to the maintenance of cell viability. Maintain sample sterility; keep all specimens at room temperature; and deliver samples to the laboratory within 24 – 48 hours. Ship specimens at room temperature for overnight delivery.

  • Unacceptable Conditions:
    • Frozen specimens
    • Specimens greater than 48 hours old*
  • Stability (collection to initiation of testing):
    • Ambient: 24 – 48 hours*
    • Frozen: Unacceptable

* Cell viability of specimens requiring cell culture may be compromised in specimens more than 48 hours old upon receipt. Refrigeration at 2° – 8° C may assist when a delay is not preventable. Do not freeze or place specimens directly on ice.


This test is used to assist in determining sex chromosome constitution in patients suspected to have conditions in which mosaicism is likely (i.e., ambiguous genitalia, Turner syndrome, etc.).


Metaphase and/or chromosome fluorescence in-situ hybridization (FISH) analyses; requires cell culture and a concurrent or previous routine karyotyping


10 – 28 days

Reference Values:

By report; interpretive