Congenital Disorder of Glycosylation Ib (MPI) Sequencing
| Disorder | Congenital Disorder of Glycosylation Ib (CDG Ib) | |
| Gene Name | MPI | |
| Clinical info | 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. | |
| Detection | Sequencing of the gene will detect over 99% of the causative mutations in patients with CDG Ib. | |
| Associated Tests | Transferrin isoelectric focusing screen Molecular testing for CDG Ia Molecular testing for CDG Ic |
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| 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 | |
| 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. | |
| Turnaround time | 21 days | |
| Prenatal testing | 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. | |
| CPT Codes | Unknown mutation 81479 Known mutation 81479 |
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| Cost | $1000 for sequencing $350 for known mutation |
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| Contact | For further information contact This email address is being protected from spambots. You need JavaScript enabled to view it. , MS, Lab Counselor at 1-800-473-9411. | |
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Kellie King, MS, CGC
Molecular Diagnostic Lab
The Molecular Diagnostic Lab offers DNA analysis for many genetic disorders via gene sequencing, targeted mutation analysis, MLPA deletion/duplication testing, trinucleotide repeat analysis and next generation sequencing panels.