|
 |
|
| Test Description |
|
Test Name
|
FISH, Williams Syndrome Microdeletion
|
|
Synonym(s)
|
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 LIMK1.
Note: Cytogenetics, Blood, Constitutional Karyotype must be ordered on the same specimen, unless cytogenetic analysis has been performed on a prior specimen |
|
Methodology
|
A fluorescently 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).
|
|
Performed
|
Daily |
|
Turnaround Time
|
8 - 10 Days |
|
Specimen Requirements
|
Minimum 3 mL aseptically collected blood in a 5 mL green top, sodium heparin tube (or 2 mL pediatric green top, sodium heparin tube). DO NOT use lithium heparin tubes.
Note: 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. |
|
CPT Code(s)
|
88271, 88273, 88291 (if routine cytogenetics not requested, add 88230) |
|
Reference Range
|
See interpretive report |
|
Contact
|
Cytogenetics Lab: (214) 645-7000
Customer Service: (214) 645-7057 or Toll Free (877) 887-8136
|
Last Modified: Jan 23, 2008 |
|
