Prader-Willi Syndrome (PWS) - RRPL
Discipline
Genetics and Genomics
Overview
Description
Ordering recommendations
- This test should be used as the first-line diagnostic test in a child with a suspected clinical diagnosis of Prader-Willi (PWS) as it provides information regarding methylation, regardless of the underlying mechanism.
Ordering requirements
- This test has been pre-approved for select medical specialties as indicated (Physician Approval to Order)
- Other physicians may inquire about getting their patient tested through the Genetics Resource Centre process
- Rush/urgent cases must be indicated on the requisition along with an e-mail to RRPLMolecularGenetics@saskhealthauthority.ca
- If this test will impact an ongoing pregnancy, also fax an urgent referral to the division of medical genetics: 306-655-1736 (otherwise see Genetic Resource Centre process)
Alias
- PWS
- SNRPN
Specimen Information
Specimen types accepted
- Whole blood: Lavender (EDTA) 4.0 mL
Specimen collection container
- Preferred collection container: Lavender (EDTA) 4.0 mL
- Alternative collection container: Microcollection - EDTA
Required volume
- Optimal volume: 8 mL
- Minimum volume: 0.5 mL
- Pediatric volume: 0.5 – 3 mL
EDTA tubes should be completely full, 2/3 full at minimum, testing may be affected by partial draw
- For patients over 20 kg: 2 EDTA tubes each containing 3.0 mL of blood
- For patients up to 20 kg: 2 EDTA tubes each containing 2.0 mL of blood
- For neonates: 1 EDTA containing a minimum of 0.5 mL of blood
Transport and stability
- Specimen specific storage and transport instructions (ex. Frozen, ship on ice, temperature specification)
- Room temperature: if being shipped on same day of collection (preferred).
- Refrigerated: If shipping is delayed
Performance
Methodology
- Purpose of test (brief): Prader-Willi/Angelman test is intended to confirm a potential cause for and clinical diagnosis of Prader-Willi syndrome (PWS), Angelman syndrome (AS), and 15q11 duplication syndrome. In rare cases, this product can also be used for carrier testing of at-risk family members. Detects copy number changes and determines methylation status. Does not distinguish between imprinting center pathogenic variants and UPD.
- How testing is performed: Referred out. 15q11 methylation sensitive MLPA
- Clinical result interpretations: Interpretation provided on report.
- Additional required information to meet accreditation standards
- Clinical interpretation
Specimen retention time
- For more information, please visit the RRPL Requisitions and Completion Aids page.
Last Updated: April 4, 2024