• Test Code:
  • Department:
    Constitutional FISH
  • Test Synonyms:
  • CPT Code(s):

Fluorescent in situ hybridization (FISH) with the ELN (elastin gene) probe detects deletion in the Williams syndrome region of 7q31.


Slides are prepared per standard protocols.  10 metaphase cells are scored per probe.  This FISH test is used as a supplement to standard G-banded chromosome analysis.

Specimen Requirements:


  • Adult - 3-5 mL drawn into a GREEN top sodium heparin vacutainer tube or into a pre-heparinized plastic syringe (use 0.2 cc sodium heparin, 1000 unit/mL).  Do NOT use lithium heparin.
  • Child - 1-2 mL, as above.
  • Infant - 1-2 mL, as above. 
  • Keep at room temperature and transport to laboratory as soon as possible.
  • Contact Client Services at (855) 535-1522 for supplies and instructions.

A REQUISITION FORM MUST ACCOMPANY ALL SAMPLES.  Please include detailed clinical information, including ethnicity, clinical history, and family history.

Test Performed (Days):

Mon - Sat

Turn Around Time:

3 - 7 days

Shipment Sensitivity Requirements:

Ship via overnight express, using the FedEx priority overnight label provided.  Use cold pack to keep specimens cool but not frozen.  Contact Client Services at (855) 535-1522 for shipping kits and instructions.


For Williams syndrome clinical and testing review see NCBI GeneReviews:

Additional Info: