Limb Girdle Muscular Dystrophy, Type 2C (LGMD2C) via the SGCG Gene
Summary and Pricing 
Test Method
Sequencing and CNV Detection via NextGen Sequencing using PG-Select Capture Probes| Test Code | Test Copy Genes | Test CPT Code | Gene CPT Codes Copy CPT Code | Base Price | |
|---|---|---|---|---|---|
| 7819 | SGCG | 81405 | 81405,81404 | $990 | Order Options and Pricing |
Pricing Comments
Testing run on PG-select capture probes includes CNV analysis for the gene(s) on the panel but does not permit the optional add on of exome-wide CNV analysis. Any of the NGS platforms allow reflex to other clinically relevant genes, up to whole exome or whole genome sequencing depending upon the base platform selected for the initial test.
An additional 25% charge will be applied to STAT orders. STAT orders are prioritized throughout the testing process.
This test is also offered via a custom panel (click here) on our exome or genome backbone which permits the optional add on of exome-wide CNV or genome-wide SV analysis.
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
Variants in the SGCG gene cause limb girdle muscular dystrophy, type 2C (LGMD2C; OMIM 253700; Noguchi et al. Science 270:819-822, 1995), formerly known as ‘severe childhood autosomal recessive muscular dystrophy’ (SCARMD). The clinical presentation of LGMD2C is marked by early-onset and severe manifestations reminiscent of Duchene muscular dystrophy. Disease onset ranges from 5 to 8 years of age (Merlini et al. Neurology 54:1075-1079, 2000; Nowak et al. Neuromusc Disord 10:100-107, 2000), with some patients unable to walk by age 12. Patients exhibit exercise intolerance, calf hypertrophy, and limb-girdle weakness. Serum CK levels are mildly to greatly elevated, and muscle biopsies demonstrate dystrophic processes and a characteristic sarcoglycan immunohistochemical profile (Bönnemann et al. Neuromusc Disord 12:273-280, 2002). A founder variant in the SGCG gene among the Romani people (Piccolo et al. Hum Mol Genet 5:2019-2022, 1996) results in a homogeneous LGMD2C phenotype consisting of early-onset weakness, calf hypertrophy, scapular winging, macroglossia, and lumbar lordosis (Merlini et al. Neurology 54:1075-1079, 2000).
Genetics
LGMD2C is inherited in an autosomal recessive manner. The SGCG gene encodes γ-sarcoglycan, a membrane-spanning subunit of the sarcoglycan complex and a component of the dystrophin-glycoprotein complex. Autosomal recessive limb girdle muscular dystrophy (LGMD2) is a genetically and clinically diverse group of muscular dystrophies. To date, 12 genes have been identified that are involved in subtypes LGMD2A-2L (see for example Laval and Bushby, Neuropathol Appl Neurobiol 30:91-105, 2004; Gordon et al. Gene Review 2009). A high incidence of LGMD2C among the Romani is caused by a p.Cys283Tyr founder variant. Missense, nonsense, and exon deletions are frequent forms of SGCG variants. Deletions of one or a few exons may represent the most common form of variant; therefore, a negative SGCG sequencing test should not be considered highly sensitive for ruling-out LGMD2C.
Clinical Sensitivity - Sequencing with CNV PG-Select
Variants in the sarcoglycan genes account for about two thirds of all childhood-onset recessive LGMD (Vainzof et al. J Neurol Sci 164:44-49, 1999), and in all but isolated populations (eg Merlini et al. Neurology 54:1075-1079, 2000), α-sarcoglycan is the most commonly affected sarcoglycan (Moore et al. J Neuropath Exp Neurol 65:995- 1003, 2006). In a cohort of 181 mostly Italian LGMD patients, seven were found to have SGCG variants by gene sequencing (Guglieri et al. Hum Mutat 29:258-266, 2008). Among a large cohort of North American LGMD patients, 2% were found to have LGMD2C based on gene sequence testing (Moore et al. 2006). However, a higher rate of SGCG variant detection has been reported when exon deletions were considered. Trabelsi et al. (Eur J Hum Genet 16:793-803, 2008) found 12 of 48 LGMD patients to have SGCG variants, three fourths of which were deletions of one or two exons.
Testing Strategy
This test provides full coverage of all coding exons of the SGCG gene, plus ~10 bases of flanking noncoding DNA. We define full coverage as >20X NGS reads or Sanger sequencing.
Indications for Test
Individuals with symptoms consistent with LGMD and individuals with immunohistochemical results demonstrating absent or prominently reduced γ-sarcoglycan with reduced but detectable immunoreactivity of the other sarcoglycans and preservation of δ-sarcoglycan (Bönnemann et al. 2002). This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in SGCG.
Individuals with symptoms consistent with LGMD and individuals with immunohistochemical results demonstrating absent or prominently reduced γ-sarcoglycan with reduced but detectable immunoreactivity of the other sarcoglycans and preservation of δ-sarcoglycan (Bönnemann et al. 2002). This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in SGCG.
Gene
| Official Gene Symbol | OMIM ID |
|---|---|
| SGCG | 608896 |
| Inheritance | Abbreviation |
|---|---|
| Autosomal Dominant | AD |
| Autosomal Recessive | AR |
| X-Linked | XL |
| Mitochondrial | MT |
Disease
| Name | Inheritance | OMIM ID |
|---|---|---|
| Muscular Dystrophy, Limb Girdle, Type 2C | AR | 253700 |
Related Tests
| Name |
|---|
| Comprehensive Cardiology Panel |
| Dilated Cardiomyopathy and Limb-Girdle Muscular Dystrophy Type 2F via the SGCD Gene |
Citations
- Bonnemann, C. G., et.al. (2002). "Primary gamma-sarcoglycanopathy (LGMD 2C): broadening of the mutational spectrum guided by the immunohistochemical profile." Neuromuscul Disord 12(3): 273-80. PubMed ID: 11801399
- Erynn Gordon, et.al. (2009). "Limb-Girdle Muscular Dystrophy Overview."
- Guglieri, M., et.al. (2008). "Clinical, molecular, and protein correlations in a large sample of genetically diagnosed Italian limb girdle muscular dystrophy patients." Hum Mutat 29(2): 258-66. PubMed ID: 17994539
- Laval SH, Bushby KMD. 2004. Limb-girdle muscular dystrophies - from genetics to molecular pathology. Neuropathology and Applied Neurobiology 30: 91-105. PubMed ID: 15043707
- Merlini, L., et.al. (2000). "Homogeneous phenotype of the gypsy limb-girdle MD with the gamma-sarcoglycan C283Y mutation." Neurology 54(5): 1075-9. PubMed ID: 10720277
- Moore SA, Shilling CJ, Westra S, Wall C, Wicklund MP, Stolle C, Brown CA, Michele DE, Piccolo F, Winder TL, Stence A, Barresi R, King N, King W, Florence J, Campbell KP, Fenichel GM, Stedman HH, Kissel JT, Griggs RC, Pandya S, Mathews KD, Pestronk A, Serrano C, Darvish D, Mendell JR. 2006. Limb-girdle muscular dystrophy in the United States. J Neuropathol Exp Neurol 65: 995-1003. PubMed ID: 17021404
- Noguchi, S., et.al. (1995). "Mutations in the dystrophin-associated protein gamma-sarcoglycan in chromosome 13 muscular dystrophy." Science 270(5237): 819-22. PubMed ID: 7481775
- Nowak, K. J., et.al. (2000). "Severe gamma-sarcoglycanopathy caused by a novel missense mutation and a large deletion." Neuromuscul Disord 10(2): 100-7. PubMed ID: 10714584
- Piccolo, F., et.al. (1996). "A founder mutation in the gamma-sarcoglycan gene of gypsies possibly predating their migration out of India." Hum Mol Genet 5(12): 2019-22. PubMed ID: 8968757
- Trabelsi, M., et.al. (2008). "Revised spectrum of mutations in sarcoglycanopathies." Eur J Hum Genet 16(7): 793-803. PubMed ID: 18285821
- Vainzof M, Passos-Bueno MR, Pavanello RC, Marie SK, Oliveira AS, Zatz M. 1999. Sarcoglycanopathies are responsible for 68% of severe autosomal recessive limb-girdle muscular dystrophy in the Brazilian population. J Neurol Sci 164: 44-49. PubMed ID: 10385046
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
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