UBE3A
Angelman syndrome is characterized by severe motor and
intellectual retardation, absence of speech, ataxia and a characteristic
open-mouthed face. Other features such as hypotonia, epilepsy and
excessive laughter help in the diagnosis of the condition. Mutations in
the ubiquitin-protein ligase E3A gene (UBE3A) located on chromosome 15
are known to be associated with a subset of Angelman syndrome cases.
UBE3A is specifically imprinted in the brain where it is only expressed
from the maternal allele. In individuals that retain the clinical
diagnosis of Angelman syndrome following normal methylation studies,
UBE3A sequencing studies should be given strong consideration. In cases
where UBE3A mutation studies identify an alteration, extended family
studies may be pursued and prenatal testing offered.
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
submitted. Prenatal analysis can be performed provided the mutations in
the family are known. CVS samples will not be accepted. Please contact
the laboratory for more information.
Transport: The specimen should be kept at room
temperature and delivered via overnight shipping. FedEx 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. Please contact Jo Anne Babb (1-800-473-9411), the molecular diagnostic
lab coordinator, for shipping information.
Analysis standards: Analysis will be complete
within 6 weeks of sample receipt. The lab director assesses the quality
and interpretation of results. Technical staff members 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 with
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 and explanations of testing protocols will be
supplied upon request.
Unknown mutation: CPT Codes: 83890, 83898
(x12), 83904 (x5), 83909 (x5), 83912
Known mutation: CPT Codes: 83890, 83898, 83904
(x2), 83909, 83912
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