Congenital Disorders of Glycosylation Type 1b
Congenital disorders of glycosylation (CDG) type 1b is
an autosomal recessive disorder caused by a deficiency of
mannosephosphate isomerase. This enzyme normally catalyzes the
conversion of mannose-6-phosphate to mannose-1-phosphate. This step is
required for the addition of N-linked sugars to proteins.
Mutational analysis of the mannosephosphate isomerase
gene (MPI) detects over 95% of the causative mutations in CDG1b
patients. Identification of the causative mutation/s in the proband can
facilitate carrier detection in interested family members.
Prenatal analysis can be performed provided the
mutations in the family are known. CVS samples will not be accepted.
Specimen requirements: 5 to10 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. 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 Tim Wood (1-800-473-9411)
for additional shipping information.
Analysis standards: Analysis will be complete
within 4 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(s): CPT Codes: 83890, 83898
(x7), 83904 (x6), 83909 (x6), 83912
Known mutation(s): CPT Codes: 83890, 83898, 83904
(x2), 83909, 83912
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