FISH ANALYSIS, DELETION 22q SYNDROME
Chromosomal Locus: 22q11.2
Pseudonyms: DiGeorge Syndrome, Velocardiofacial Syndrome, Shprintzen Syndrome, Conotruncal Anomaly Face Syndrome
TURNAROUND TIME: 7 to 10 days
TESTING METHODOLOGY: Fluorescence in situ hybridization
- Collect: 3-5 mL peripheral blood in sodium heparin (green) for children and adults; 1-2 mL peripheral blood in sodium heparin (green) for newborns.
- Min. Collection: 1 mL for newborns; 2 mL for children and adults
- Transport: peripheral blood in sodium heparin (green) at 20-25°C
- Stability: Ambient: 24 hours; Refrigerated: 72 hours; Frozen: unacceptable
- Unacceptable Conditions: Frozen or clotted specimens; specimens in anticoagulants other than sodium heparin.
Test Summary: Test can detect microdeletions of the DiGeorge/velocardiofacial syndrome critical region in 22q11.2. More than 95% of patients with the Deletion 22q syndrome have a deletion detectable by FISH.
Methods: A dual-color FISH analysis performed on metaphase cells using a probe for the TUPLE1 locus in chromosome 22q11.2 and a chromosome 22 control probe; analysis of 10 metaphase cells and 20 interphase cells.
Indications for Use:
- Patients suspected of having Deletion 22q, DiGeorge or Velocardiofacial syndrome on the basis of clinical findings such as congenital heart disease (particularly conotruncal malformations), palatal abnormalities (particularly velopharyngeal insufficiency), hypocalcemia, immune deficiency, developmental delay, characteristic facial features.