FISH ANALYSIS, ANGELMAN SYNDROME
Chromosomal Locus: 15q11.2
Pseudonyms: 15q11.2 deletion, UBE3A gene deletion
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 D15S10/UBE3A locus in 15q11.2. Approximately 70% of patients with Angelman syndrome have deletions of D15S10/UBE3A.
Methods: A dual-color FISH analysis performed on metaphase cells using probes for the UBE3A in 15q11.2 and for the D15Z1 and the PML control loci ; analysis of 10 metaphase cells and 20 interphase cells
Test Limitations: The test does not detect other causes of Angelman syndrome such as paternal uniparental disomy, imprinting defects or mutations of the UBE3A gene.
Indications for Use:
- Patients suspected of having Angelman syndrome on the basis of clinical findings such as facial dysmorphology, gait ataxia, frequent laughter, failure to learn speech, microcephaly, or severe developmental delay.
- Patients with a positive DNA methylation test for Angelman syndrome.