Molecular Genetics Duchenne/Becker Muscular Dystrophy, DMD/BMD, Deletion/Duplication

Duchenne muscular dystrophy (DMD) is a severe X-linked recessive neuromuscular disorder that occurs in approximately one in every 3,000 male newborns and infrequently affects females. DMD is characterized by the complete absence of dystrophin, a structural protein integral to normal muscle function. The molecular defect in most DMD patients is an out of frame deletion within the dystrophin gene, and duplications also occur. Becker muscular dystrophy (BMD) is a milder allelic form, also characterized by primarily deletion type mutations (generally in frame) as well as duplications.  Deletion/duplication analysis will detect the majority of mutations in DMD/BMD patients. The remainder of mutations, about 25-30% in DMD and about 15% in BMD patients are due to point mutations, which require sequence analysis.

Reasons for Referral:

• Confirmation of clinical diagnosis of DMD, BMD
• Carrier identification in mothers of affected males and at risk females with family history of DMD or BMD
• Prenatal testing for females who carry an identified dystrophin mutation

A customized CytoSure “exon-centric” array (Oxford Gene Technology) will be used to detect deletions and duplications.  The targeted array has enhanced probes targeted to the exonic regions of DMD.  The arrays are run using Agilent SureScan technology.

Blood:  EDTA or ACD (solution A or B):

• Adult:5mL
• Child:5mL
• Infant:2-3mL

Saliva: 2 ORAgene Saliva Kits (OGR-500) used according to manufacturer instructions.  Please contact KDL Client Services for a Saliva Collection Kit for patients that cannot provide a blood sample.

Assisted Saliva: 4 ORAgene Assisted Saliva Kits (OGR-575) used according to manufacturer instructions.  Please contact KDL Client Services for an Assisted Saliva Collection Kit for patients that cannot provide a blood sample.

Skin Fibroblast: Punch Biopsy (cell cultures will be prepared at KDL and used for testing), or 2 T-25 confluent flasks

Prenatal:

• Direct Amniotic Fluid (10-20mL)
• Direct CVS
• Cultured Amniocytes (2 T-25 flasks)
• Cultured CVS (2 T-25 flasks)
• Cultured Fetal Tissue: Product of Conception (2 T-25 flasks)
• Cord Blood (1-2mL)

DNA: 5-10µg at a minimum of 60-100ng/µL (DNA must be extracted in a CLIA-certified laboratory or a laboratory meeting equivalent requirements as determined by the CAP and/or CMS)

Notice Regarding Molecular Genetic Testing on CVS or Amniotic Fluid Specimens:

• Maternal cell rule-out testing will be performed on all prenatal specimens received.Please provide maternal blood in addition to the fetal specimen.Additional charges apply for the maternal cell rule-out test.
• All genetic testing performed on Direct CVS or Direct Amniotic Fluid specimens will be confirmed on cell cultures prepared by Knight Diagnostic Laboratories.Cell cultures will be prepared from the specimen received.Additional charges apply for confirmatory testing.

For routine testing of blood and saliva (or DNA extracted from them), KDL does NOT accept samples from patients within two (2) weeks of a packed cell/platelet transfusion or within four (4) weeks of a whole blood transfusion.  For extraordinary circumstances, where testing must be performed outside of the above windows, please contact our lab.

A REQUISITION FORM MUST ACCOMPANY ALL SAMPLES.  Please include detailed clinical information, including ethnicity, clinical history, and family history.

Weekly

14 - 21 Days

• Keep specimen cold during transit, but do not ship on dry ice. 
• Contact Client Services for shipping kits and instructions. 
• Please use the cold pack provided in the KDL shipping kit. 
• Ship the specimen overnight express, using the FedEx priority overnight label provided.

1. National Institute of Neurological Disorders and Stroke, What is Muscular Dystrophy, http://www.ninds.nih.gov/disorders/md/md.htm.

Genetic counseling is indicated for affected individuals and their families.
Please contact Client Services at (855) 535-1522 for more information.