Test Description:
Angelman syndrome (AS) is a genetic disorder that affects approximately 1 in 15,000 individuals and causes severe developmental delay with minimal or no speech. Affected individuals also have a movement or balance disorder presenting as an ataxic gait or tremulous limb movements. Unique behaviors such as frequent laughter and uplifted, flexed arms when walking are common. Microcephaly and seizures are present in most.
This test is abnormal in 78% of individuals with AS, including those with a deletion, uniparental disomy or an imprinting defect. A normal result detects both a maternal allele and paternal allele. Absence of the maternal allele confirms the diagnosis of Angelman syndrome. If the result is abnormal, fluorescence in situ hybridization (FISH) testing of the Angelman critical region will be offered to determine recurrence risk information.
Methods:
Methylation-specific multiplex PCR of the SNRPN gene is followed by gel electrophoresis to analyze for the presence of maternal or paternal alleles. The normal PCR products are 174 base pairs and 100 base pairs, respectively. The maternally-derived 174 base pair band is absent in patients with Angelman syndrome. Rarely, deletions, chromosome rearrangements or point mutations may occur that are undetectable by this assay.
Specimen Requirements:
5-7 ml (2 ml for infants) of whole blood in an EDTA (purple top) tube.
Shipping Instructions:
Ship unprocessed sample at ambient or refrigerated temperature (DO NOT FREEZE) to the MSU DNA Diagnostic Laboratory, B123 Life Sciences Bldg., East Lansing, MI 48824. Call (517)353-2032 or 1-877-TEST-DNA with any questions. Specimen must arrive within 24 hours of collection.
Turnaround Time: 7 to 10 days
Test CPT Codes: 83891, 83892, 83900, 83894, 83912