Veripath Test Directory

Synonyms Prader-Willi Syndrome Microdeletion FISH
Description Fluorescence In Situ Hybridization (FISH) Is performed to detect microdeletlons of chromosome 15 at band 15q11.2q13, as seen In about
70% of patients with Prader-Willi syndrome. Prader-Willi caused by maternal uniparental disomy or methylation abnormalities will not be detected.
Specimen Requirements 
Container Green top (sodium heparin) collection tube
Specimen Type Blood
Preferred Collection Volume 3 mL
Minimum Collection Volume 2 mL
Collection Instructions 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.
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.
Methodology A fluorescent labeled DNA probe set, SNRPN, which maps to the minimal deletion interval critical for Prader-Willi syndrome, 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) 88271x2, 88273, 88291(if routine cytogenetics not requested, add
Department Cytogenetics
Contact Information Cytogenetics 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 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