• Test Code:
    1280
  • Department:
  • Test Synonyms:
    Becker Muscular DystrophyDuchenne Muscular DystrophyDMDBMDDystrophin
  • CPT Code(s):
    81161
Background:

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

Methodology:

Multiple ligation-dependent probe amplification (MLPA) of all exons in the dystrophin gene.  A negative test in patients with strong clinical suspicion of DMD or BMD should be followed by dystrophin gene sequencing.

Specimen Requirements:

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

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

DNA: 10µg at a minimum of 100ng/µL

Prenatal specimens: Both direct and cultured amniocytes or chorionic villi.  All direct tests are confirmed using cultured cells.  Please contact Client Services at (855) 535-1522 to arrange for cell culturing in our cytogenetics laboratory (a minimum of 2 T25 flasks). 

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

Test Performed (Days):

Weekly

Turn Around Time:

7 – 14 Days

Shipment Sensitivity Requirements:

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.

References:

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

Additional Info:

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

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