Duchenne and Becker Muscular Dystrophy
Both Duchenne and the milder Becker muscular dystrophy are
due to mutations in the dystrophin gene located on the X chromosome.
The characteristic features of these disorders include pseudohypertrophy
of the calf muscle, myofiber degeneration, myopathic EMG changes,
and dramatic elevations of serum creatine kinase. Approximately
two-thirds of disease causing mutations in the dystrophin gene
are due to deletions and duplications. The majority of the remaining
dystrophin defects result from point mutations within the gene.
Testing for Duchenne and Becker muscular dystrophy at the Greenwood
Genetic Center involves multiple ligation-dependent probe amplification (MLPA) analysis that can detect
up to 98% of all deletions and duplications in muscular dystrophy
patients and in females that carry the mutation. Linkage analysis
is also available for families with unknown mutations in the
dystrophin gene. Prenatal testing is available via material from
CVS or amniocentesis.
Specimen requirements: 5 to 10 ml of peripheral blood
collected in an EDTA (lavender top) Vacutainer tube is preferred.
The minimal blood needed for reliable DNA isolation is 3 ml.
If necessary, ACD solution A Vacutainer tubes (yellow top)
may be substituted. Prenatal studies require two confluent T-25
flasks containing cultured CVS material or amniocytes. A maternal
blood sample is also requested for prenatal analysis.
Transport: Please contact the Molecular Diagnostic Laboratory
Coordinator (1-800-473-9411) for shipping
information. The specimen should be kept at room temperature
and delivered via overnight shipping. FedEx delivery is preferred.
If shipment is delayed by one or two days, the specimen should
be refrigerated and shipped at room temperature. Do not freeze
the specimen. Samples collected on a Friday can be safely
designated for Monday delivery.
Analysis standards: Analysis will be completed within
2 weeks from sample receipt. The quality and interpretation of
test results are assessed by the laboratory director. Technical
staff independently assess the quality and interpretation of
the test. The Greenwood Genetic Center Molecular Diagnostic Laboratory
is CLIA certified and actively participates in CAP proficiency
surveys.
Reporting of Test Results: Test results and their interpretation
will be mailed and/or faxed following completion of the test.
Verbal reports will be telephoned to the person(s) requesting
the test when an abnormal test result occurs. Consultation with
the laboratory director is available and explanations of testing
protocols will be provided upon request.
CPT Codes: 83890, 83892,
83900, 83901 (x10), 83909, 83912
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