MECP2 Deletion and Duplication Analysis by MLPA
Rett syndrome is a neurodevelopmental disorder that
affects mostly females. The condition is associated with cortical atrophy,
stereotypical hand movements and severe mental retardation. With an
incidence of 1/10,000 - 15,000, it is one of the most common causes of
mental retardation in females. Approximately 80% of individuals with a
classic Rett syndrome phenotype will have a detectable mutation by
sequencing the MECP2 gene.
Further testing is available for individuals who test negative
via sequencing, but continue to carry a clinical diagnosis of Rett syndrome.
Large MECP2 deletions and duplications that are not detectable by sequencing can
be detected using multiplex ligation-dependant probe amplification (MLPA)
analysis. Of those females who have a normal sequencing result, approximately
15% will have a deletion or duplication detectable by MLPA.
Additionally, a specific phenotype has been identified in
males with a MECP2 duplication that is identifiable by MLPA. These males display
hypotonia that progresses to spasticity, severe mental retardation and recurrent
pulmonary infections. Females in these families who have the duplication are
clinically unaffected and display a near total skewing of X-inactivation.
Specimen requirements: 5 to 10 ml of peripheral blood
collected in an EDTA (lavender top) Vacutainer tube is preferred. The minimal
amount needed for reliable DNA isolation is 3 ml. If necessary, ACD solution A
Vacutainer tubes (yellow top) may be substituted. If MECP2 sequencing was
performed at the Greenwood Genetic Center, an additional blood sample may not be
necessary. Please contact JoAnne Babb for more information (1-800-473-9411)
Transport: 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 Friday can be safely designated for Monday delivery.
Analysis standards: Analysis will be completed within
2-3 weeks from sample receipt. The quality and interpretation of the test
results are assessed independently by the technical staff and laboratory
director. The Greenwood Genetic Center Molecular Diagnostic Laboratory is CLIA
certified and actively participates in CAP proficiency surveys.
Reporting of Test Results: Test results with
interpretation will be mailed and/or faxed following the 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 and
explanations of testing protocols will be supplied upon request.
CPT codes: 83890, 83892, 83900, 83901(x10), 83909,
83912
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