Veripath Test Directory

Synonyms Williams Syndrome Microdeletion FISH
Description Fluorescence In Situ Hybridization (FISH) is performed to detect microdeletions in the Williams syndrome critical region at chromosome band 7q11.23. Deletions of the elastin gene are seen in approximately
96% of classic Williams syndrome patients and are most often
accompanied by concomitant deletion of UMK1.
Specimen Requirements 
Container Green top (sodium heparin) collection tube
Specimen Type Blood
Preferred Collection Volume 3 mL
Minimum Collection Volume 2 mL
Collection Instructions
Specimen Handling 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.
Rejection Criteria Frozen, clotted, hemolyzed or grossly contaminated specimens. Incorrect anticoagulant used. Specimen collected in lithium heparin.
Methodology A fluorescent labeled DNA probe cocktail containing probes for the elastin gene (ELN) which is implicated in the vascular disease present in Williams syndrome patients, the LIMK1 gene which is implicated in the neurological features of the disease, and the anonymous sequence, D7S613, which is telomeric to the LIMK1 locus is hybridized to unstained metaphase chromosomes. Ten cells are evaluated for the presence of 2 signals (normal) or 1 signal (deletion).
Reference Range See interpretive report.
CPT Code(s) 88271, 88273, 88291 (if routine cytogenetics not requested, add 88230)
Department Cytogenetics
Contact Information Lab: (214) 648-0975, Customer service: (214) 645-7057 or Toll free: (877)-887-8136
Turn Around Time7-10 days
Performed Sunday - Saturday
Performed by Cytogenetics
Notes Note: "Cytogenetics. Blood, Constitutional Karyotype" must be ordered on the same specimen, unless cytogenetic analysis has been performed on a prior specimen
Updated/Reviewed 12/12/2016