Facioscapulohumeral Muscular Dystrophy - RRPL
Discipline
Genetics and Genomics
Overview
Description
Ordering recommendations
- This test can used to look for Facioscapulohumeral muscular dystrophy type 1 (FSHD1); an autosomal dominant form of muscular dystrophy caused by a contraction of the D4Z4 repeat array in the subtelomeric region of chromosome 4q35.
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
- FSHD, D4Z4
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
Collection procedure
- Must be drawn on Monday or Tuesday
Required volume
- Optimal volume: 16 mL
- Minimum volume: Send out lab required 4 tubes.
- 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): This assay can identify approximately 95% individuals affected with FSHD caused by a contraction of D4Z4 repeats at 4q35.
- How testing is performed: Referred out. FSHD analysis pipeline is used to size the D4Z4 repeat arrays on chromosomes 4 and 10, as well as to assign the permissive and non-permissive haplotypes. The accuracy of sizing is approximately +/- 1 unit. Copy number variants in the proximity of the SMCHD1 gene on chromosome 18 may also be detected and reported.
- Clinical result interpretations: Interpretation provided on report.
Specimen retention time
- For more information, please visit the RRPL Requisitions and Completion Aids page.
Last Updated: March 28, 2024