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Test Code MD DNA Duchenne/Becker Muscular Dystrophy Del/Dup

Clinical System Name

Muscular Dystrophy DNA Analysis

Synonyms

Duchenne/Becker Muscular Dystrophy Request

Becker Muscular Dystrophy Mutation Analysis

DMD/BMD Deletion/Duplication Analysis

Duchenne Muscular Dystrophy Mutation Analysis

Dystrophin

Duchenne/Becker Muscular Dystrophy Del/Dup Request

DMD DelDup

Description

The dystrophinopathies are a spectrum of muscle diseases, with onset from childhood to adulthood and of varying severity. Duchenne muscular dystrophy (DMD) is the most frequent muscle disease in children.  DMD and Becker muscular dystrophy (BMD) are X-linked recessive diseases caused by mutations in the DMD gene that encodes the dystrophin protein.

 

This test is indicated for males with a clinical diagnosis or symptoms of Duchenne or Becker muscular dystrophy, or females who are at risk to be a carrier. Prenatal testing is available to females who carry an identified DMD mutation.

Sample Requirements

Specimen: Whole blood, cord blood

Container(s): Lavender/EDTA, Yellow/ACD A or B

Preferred Vol: 3 mL

Minimum Vol: 1 mL

 

Note: Heparin samples (Green tops) are unacceptable.

  

Specimen: Cultured cells

Acceptable:  Fibroblasts

Container(s): T-25 flasks

Preferred Vol: 2 flasks

Processing Instructions

Reject due to: Heparin

Spin: No

Aliquot: No

Temp: Refrigerate

Storage location: Molecular Genetics box in CPA refrigerator #2

 

Off-site collection: Refrigerate blood samples until ready to ship.  Transport all sample types at room temperature via overnight shipping.

Stability

Specimen Type Temperature Time
Cultured cells Room temp 3 days
Whole blood Room temp 3-5 days
Whole blood Refrigerated 7 days

 

Note: Whole blood samples > 7days may be submitted to be assessed by our lab for acceptability for testing.

Availability

STAT Performed TAT
Contact lab Monday - Friday 2-3 weeks

 

Performing Laboratory

Seattle Children's Laboratory

Department

Department:  Molecular Genetics Laboratory

Phone: 206-987-3872

 

Lab Client Services: 206-987-2617

 

Lab Genetic Counselor: LabGC@seattlechildrens.org

Reference Range

Interpretive report will be provided

Methodology

Method: Multiple ligation-dependent probe amplification (MLPA) of all exons in the DMD gene.

 

This technique will detect >99% of deletions and duplications associated with Duchenne/Becker muscular dystrophy. Recognized deletions of the DMD gene are found in approximately 65% of individuals with the clinical diagnosis of Duchenne muscular dystrophy (DMD) and approximately 85% of individuals with the clinical diagnosis of Becker muscular dystrophy (BMD). Recognized duplications for both DMD and BMD are found in approximately 6-10% of individuals. A negative test in patients with strong clinical suspicion of DMD or BMD should be followed by DMD gene sequencing.

Limitations: Point mutations within the DMD gene are not detected by this method.

CPT Codes

81161 (updated 2/3/16 by jconta)

Special Instructions

Links to: Dystrophinopathy GeneReview

Requisition

Molecular Genetics

Clinical Utility

The dystrophinopathies are a spectrum of muscle diseases, with onset from childhood to adulthood and of varying severity. Duchenne muscular dystrophy (DMD) is the most frequent muscle disease in children. The birth prevalence of DMD is around 1 in 3500 live born males. The milder Becker muscular dystrophy (BMD) has a lower birth prevalence of around 1 in 18,500 live born males. DMD and BMD are X-linked recessive diseases caused by mutations in the DMD gene that encodes the dystrophin protein. More recently, DMD-associated cardiomyopathy (DCM) with congestive heart failure has been identified, which can occur in males age 20-40 on average and in female carriers later in life. Males with DCM typically do not have muscle weakness and are often diagnosed as ‘subclinical BMD’.
 

Deletions in the DMD gene make up approximately 65% of mutations in individuals with DMD and about 85% of mutations in BMD. Duplications make up 6-10% of mutations in individuals with DMD or BMD.

Using multiplex ligation-dependent probe amplification (MLPA), this test will detect >99% of deletions and duplications in the dystrophin gene, leading to an overall detection rate of about 70-75% for DMD and 90-95% for BMD. A negative test in patients with strong clinical suspicion of DMD or BMD should be followed by DMD gene sequencing