Dystroglycanopathy via the GMPPB Gene
Summary and Pricing 
Test Method
Exome Sequencing with CNV Detection
| Test Code | Test Copy Genes | Test CPT Code | Gene CPT Codes Copy CPT Code | Base Price | |
|---|---|---|---|---|---|
| 10009 | GMPPB | 81479 | 81479,81479 | $990 | Order Options and Pricing |
Pricing Comments
Our favored testing approach is exome based NextGen sequencing with CNV analysis. This will allow cost effective reflexing to PGxome or other exome based tests. However, if full gene Sanger sequencing is desired for STAT turnaround time, insurance, or other reasons, please see link below for Test Code, pricing, and turnaround time information. If the Sanger option is selected, CNV detection may be ordered through Test #600.
An additional 25% charge will be applied to STAT orders. STAT orders are prioritized throughout the testing process.
Click here for costs to reflex to whole PGxome (if original test is on PGxome Sequencing platform).
Click here for costs to reflex to whole PGnome (if original test is on PGnome Sequencing platform).
The Sanger Sequencing method for this test is NY State approved.
For Sanger Sequencing click here.Turnaround Time
3 weeks on average for standard orders or 2 weeks on average for STAT orders.
Please note: Once the testing process begins, an Estimated Report Date (ERD) range will be displayed in the portal. This is the most accurate prediction of when your report will be complete and may differ from the average TAT published on our website. About 85% of our tests will be reported within or before the ERD range. We will notify you of significant delays or holds which will impact the ERD. Learn more about turnaround times here.
Targeted Testing
For ordering sequencing of targeted known variants, go to our Targeted Variants page.
Clinical Features and Genetics
Clinical Features
Mutations in a growing number of proven or putative glycosyltransferase genes and one putative lipid biosynthesis gene (ISPD, Willer et al. 2012; Roscioli et al. 2012) cause muscular dystrophies in the dystroglycanopathy spectrum. Walker-Warburg syndrome (WWS, OMIM 236670), a severe congenital muscular dystrophy with defective neuronal migration and associated structural brain and eye abnormalities, is the most severe manifestation. Other presentations include muscle-eye-brain disease (MEB; OMIM 253280), Fukuyama congenital muscular dystrophy (FCMD, OMIM 253800), and congenital or limb girdle muscular dystrophy with associated mental retardation (MR), but without structural brain abnormalities (eg., LGMD2K, OMIM 609308 and CMD-MR, respectively (Godfrey et al. 2007). At the mild side of the spectrum is LGMD2I (OMIM 607155), which may first present in adulthood.
A newly discovered gene, GMPPB, has been found to be causative for limb-girdle and congenital muscular dystrophies with hypoglycosylation of alpha dystroglycan (Carss et al 2013). Clinical phenotypes of patients with GMPPB mutations range from muscle-eye-brain disease to a limb girdle muscular dystrophy with onset in early childhood and with normal intellectual exam (Carss et al. 2013). Four patients from Southern Italy were described with delayed cognitive development, absent speech, microcephaly, myopathic facies, and seizures (Messina et al. 2009; Carss et al. 2013). All reported patients have been found to have greatly elevated CpK levels, dystrophic muscle biopsies, and reduced glycosylation of alpha dystroglycan (Carrs et al. 2013).
Genetics
GMPPB-associated dystroglycanopathy is inherited as an autosomal recessive disorder. Thus far, causative missense and nonsense mutations have been reported (http://www.LOVD.nl/GMPPB). GDP-mannose pyrophosporylase B is encoded by the GMPPB gene (OMIM 615320) and is an enzyme required for O-mannosylation of alpha dystroglycan.
Clinical Sensitivity - Sequencing with CNV PGxome
Dystroglycanopathy is a genetically heterogeneous disorder. Too few cases for GMPPB related dystroglycanopathy have been reported to estimate clinical sensitivity. Analytical sensitivity may be high because all mutations reported to date are detectable by gene sequencing methods.
Testing Strategy
This test provides full coverage of all coding exons of the GMPPB gene plus 10 bases of flanking noncoding DNA in all available transcripts along with other non-coding regions in which pathogenic variants have been identified at PreventionGenetics or reported elsewhere. We define full coverage as >20X NGS reads or Sanger sequencing. PGnome panels typically provide slightly increased coverage over the PGxome equivalent. PGnome sequencing panels have the added benefit of additional analysis and reporting of deep intronic regions (where applicable).
Dependent on the sequencing backbone selected for this testing, discounted reflex testing to any other similar backbone-based test is available (i.e., PGxome panel to whole PGxome; PGnome panel to whole PGnome).
Indications for Test
Individuals with muscular dystrophy in the dystroglycanopathy spectrum. Individuals with immunofluorescence results demonstrating hypoglycosylation of alpha dystroglycan in muscle. This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in GMPPB.
Individuals with muscular dystrophy in the dystroglycanopathy spectrum. Individuals with immunofluorescence results demonstrating hypoglycosylation of alpha dystroglycan in muscle. This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in GMPPB.
Gene
| Official Gene Symbol | OMIM ID |
|---|---|
| GMPPB | 615320 |
| Inheritance | Abbreviation |
|---|---|
| Autosomal Dominant | AD |
| Autosomal Recessive | AR |
| X-Linked | XL |
| Mitochondrial | MT |
Diseases
Citations
- Carss KJ, Stevens E, Foley AR, Cirak S, Riemersma M, Torelli S, Hoischen A, Willer T, Scherpenzeel M van, Moore SA, Messina S, Bertini E, et al. 2013. Mutations in GDP-Mannose Pyrophosphorylase B Cause Congenital and Limb-Girdle Muscular Dystrophies Associated with Hypoglycosylation of α-Dystroglycan. The American Journal of Human Genetics 93: 29–41. PubMed ID: 23768512
- Godfrey C, Clement E, Mein R, Brockington M, Smith J, Talim B, Straub V, Robb S, Quinlivan R, Feng L, Jimenez-Mallebrera C, Mercuri E, et al. 2007. Refining genotype phenotype correlations in muscular dystrophies with defective glycosylation of dystroglycan. Brain 130: 2725–2735. PubMed ID: 17878207
- Leiden Open Variation Database- GMPPB.
- Messina S, Tortorella G, Concolino D, Spanò M, D’Amico A, Bruno C, Santorelli FM, Mercuri E, Bertini E. 2009. Congenital muscular dystrophy with defective α-dystroglycan, cerebellar hypoplasia, and epilepsy. Neurology 73: 1599–1601. PubMed ID: 19901254
- Roscioli T, Kamsteeg E-J, Buysse K, Maystadt I, Reeuwijk J van, Elzen C van den, Beusekom E van, Riemersma M, Pfundt R, Vissers LELM, Schraders M, Altunoglu U, et al. 2012. Mutations in ISPD cause Walker-Warburg syndrome and defective glycosylation of α-dystroglycan. Nature Genetics 44: 581–585. PubMed ID: 22522421
- Willer T, Lee H, Lommel M, Yoshida-Moriguchi T, Bernabe DBV de, Venzke D, Cirak S, Schachter H, Vajsar J, Voit T, Muntoni F, Loder AS, et al. 2012. ISPD loss-of-function mutations disrupt dystroglycan O-mannosylation and cause Walker-Warburg syndrome. Nature Genetics 44: 575–580. PubMed ID: 22522420
Ordering/Specimens
Ordering Options
We offer several options when ordering sequencing tests. For more information on these options, see our Ordering Instructions page. To view available options, click on the Order Options button within the test description.
myPrevent - Online Ordering
- The test can be added to your online orders in the Summary and Pricing section.
- Once the test has been added log in to myPrevent to fill out an online requisition form.
- PGnome sequencing panels can be ordered via the myPrevent portal only at this time.
Requisition Form
- A completed requisition form must accompany all specimens.
- Billing information along with specimen and shipping instructions are within the requisition form.
- All testing must be ordered by a qualified healthcare provider.
For Requisition Forms, visit our Forms page
If ordering a Duo or Trio test, the proband and all comparator samples are required to initiate testing. If we do not receive all required samples for the test ordered within 21 days, we will convert the order to the most effective testing strategy with the samples available. Prior authorization and/or billing in place may be impacted by a change in test code.
Specimen Types
Specimen Requirements and Shipping Details
PGxome (Exome) Sequencing Panel
PGnome (Genome) Sequencing Panel
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ORDER OPTIONS
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2) Select Additional Test Options
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