Congenital Disorder of Glycosylation 1b : MPI Sequencing

Test Information

MPI sequencing is a molecular test used to identify variants in the gene associated with Congenital Disorder of Glycosylation 1b.

Turnaround Time

3 weeks

CPT Code(s)

81405

Cost

$1,000

Genes

Clinical Information

Congenital disorder of glycosylation (CDG) Ib 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. CDG Ib is unique among the known congenital disorders aof glycosylation by lacking significant CNS involvement. Patients may present with chronic diarrhea, failure to thrive and protein-losing enteropathy. Hepatic fibrosis may also develop. CDG Ib can be effectively treated with oral mannose supplementation.

Indications

Molecular testing is useful to confirm the diagnosis and to identify the disease causing mutations within a family to allow for carrier testing and prenatal diagnosis.

Methodology

Sanger Sequencing

Detection

Sequencing of the gene will detect over 99% of the causative mutations in patients with CDG Ib.

Specimen Requirements

5 to 7 ml of peripheral blood collected in an EDTA (lavender top) tube is the preferred specimen type. The minimal blood needed for reliable DNA isolation is 3 ml. Extracted DNA, dried blood spots, and saliva are also accepted for this test.

Transport Instructions

The specimen should be kept at room temperature and delivered via overnight shipping. 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.

Prenatal Testing Information

Prenatal diagnosis is available if the familial mutations are known. Additional fees for cell culture and maternal cell contamination may apply. Maternal cell contamination studies are required for all prenatal molecular tests. Contact the laboratory prior to sending a prenatal specimen.

Have Questions Need Support?

Call our laboratory at 1-800-473-9411 or contact one of our Laboratory Genetic Counselors for assistance.
Robin Fletcher, MS, CGC
Kellie Walden, MS, CGC

Sanger Sequencing
Meet Reggie Roper

Meet Reggie Roper

Reggie has been part of the GGC family for over 18 years. He has short stature, webbing of his hands, pulmonary stenosis, seizures and hydrocephalus along with developmental delay. He carried an initial diagnosis of cardiofaciocutaneous (CFC) syndrome; however, as genetic testing advanced, GGC made the diagnosis of Noonan-like syndrome with loose anagen hair by identifying a mutation in the SHOC2 gene. He is also an active participant in the Greenwood Community Theatre's Penguin Project. "GGC is...

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