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Angelman Syndrome

Gene name / Alternate gene name
Methylation and Copy Number Analysis
Small nuclear ribonucleoprotein polypeptide N
Lab area
Genome Diagnostics - Molecular Genetics
Method and equipment
Methylation-Specific-MLPA of SNPRN
UPD15 via STR (short tandem repeat) analysis
Expected turn-around time
Pregnancy/STAT: 2-3 weeks Routine: 4-6 weeks
Specimen type

Blood; extracted DNA is not accepted for this test.

For details about specimen requirements, please refer to: Specimen Types & Requirements (PDF).

Specimen requirements
  • 5-10 mL EDTA
  • 0.5 mL EDTA (neonate)
Storage and transportation

Room Temperature

For details about specimen requirements, please refer to: Specimen Type and Requirements

DNA extracted at an external lab is not accepted for MS-MLPA testing.

Special requirements

Special Instructions for Genome Diagnostics Samples

If sample shipment  >48 hours, ship on ice.

Shipping information
The Hospital for Sick Children
Division of Genome Diagnostics
555 University Avenue, Black Wing, Room 3416
Toronto, ON
M5G 1X8
Phone: 416-813-7200 ext. 2
Hours: Monday to Friday, 8 a.m. to 4:30 p.m.
Off hours: Please send to Rapid Response Laboratory, 555 University Avenue, Room 3642
Email Molecular Lab:
Email Cytogenetics:
Background and clinical significance

Angelman syndrome (AS) is characterized by severe developmental delay or intellectual disability, severe speech impairment, gait ataxia and/or tremors in the limbs. Microcephaly and seizures are common. Affected individuals also display characteristic demeanor that includes inappropriate laughing, smiling, and excitability.

There are a number of genetic changes that cause AS, although each produces a similar clinical phenotype. Approximately 70% of cases are the result of a deletion in the maternally contributed chromosome 15q11-q13 region. Approximately 5% of cases have received two copies of chromosome 15 from their father and none from their mother: paternal uniparental disomy (patUPD). Like the deletion patients, paternal UPD patients are deficient for maternally derived genes in the AS critical region. Approximately 5% of patients have an 'imprinting mutation' which alters the normal expression of maternal genes in the AS critical region. Approximately 20% of clinically diagnosed AS patients have genetic alterations other than deletion, UPD or imprinting mutations. These mutations are not detected by methodology currently in place in the Molecular Genetics Laboratory, and samples may be referred to a research lab for further investigation.

DNA in the AS critical region is methylated. If the normal expression of genes in the critical region is altered due to deletion, UPD or imprinting mutations, the methylation pattern is also changed. Testing the methylation status of genes within the critical region therefore allows these genetic alterations to be detected. For molecular analysis, the methylation status of the gene SNRPN within the AS critical region is measured. Abnormal methylation of the maternally derived gene is diagnostic of Angelman syndrome.

See related information sheet Angelman Syndrome

Disease condition

Angelman Syndrome

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