Limb Girdle Muscular Dystrophy, Type 2D (LGMD2D) via the SGCA 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 | |
|---|---|---|---|---|---|
| 7815 | SGCA | 81405 | 81405,81479 | $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 SGCA gene (OMIM 600119) cause limb girdle muscular dystrophy type 2D (LGMD2D; OMIM 608099; Roberds et al. Cell 78:625-633, 1994). LGMD2D presents with a progressive clinical course and limb weakness. Proximal muscles are affected more than distal muscles. Age of onset and clinical severity of LGMD2D ranges from a Duchenne-like presentation with cardiomyopathy and congestive heart failure to mild, steroid-responsive limb girdle muscular dystrophy (Angelini et al. Muscle Nerve 21:769-775, 1998). Serum creatine kinase levels are typically elevated, and muscle biopsies demonstrate a dystrophic process. Immunofluorescence or western blot analysis will detect absence or reduction of α-sarcoglycan but normal dystrophin staining. Secondary deficiency of the other sarcoglycans may be observed. SGCA gene replacement therapy in LGMD2D patients has been reported (Mendell et al. Ann Neurol 68:629-638, 2010).
Genetics
LGMD2D is inherited in an autosomal recessive manner. The SGCA gene encodes α-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. GeneReviews, 2009). A negative SGCA sequencing result does not rule out a diagnosis of limb girdle muscular dystrophy when classic clinical findings are present. A comprehensive approach including epidemiology, medical history, clinical exam, muscle biopsy and other labs, and genetic testing is recommended for precise diagnosis of the limb girdle muscular dystrophies (Guglieri and Bushby Neurol India 56:271-280, 2009).
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 (e.g. 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). The SGCA c.229C>T (p.Arg77Cys) variant represents at least one-third of all disease-causing alleles in LGMD2D patients from wide geographic origins (Duggan et al. N Engl J Med 336:618-624, 1997; Carrie et al. J Med Genet 34:470-475, 1997). In a study of LGMD patients in the USA, the c.229C>T (p.Arg77Cys) variant was found in 11 of 24 mutant chromosomes from 12 unrelated LGMD2D patients (Moore et al. 2006).
Testing Strategy
This test provides full coverage of all coding exons of the SGCA 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. Individuals with immunofluorescence results demonstrating reduced staining of α-sarcoglycan in muscle. This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in SGCA.
Individuals with symptoms consistent with LGMD. Individuals with immunofluorescence results demonstrating reduced staining of α-sarcoglycan in muscle. This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in SGCA.
Gene
| Official Gene Symbol | OMIM ID |
|---|---|
| SGCA | 600119 |
| Inheritance | Abbreviation |
|---|---|
| Autosomal Dominant | AD |
| Autosomal Recessive | AR |
| X-Linked | XL |
| Mitochondrial | MT |
Disease
| Name | Inheritance | OMIM ID |
|---|---|---|
| Limb-Girdle Muscular Dystrophy, Type 2D | AR | 608099 |
Related Test
| Name |
|---|
| Dilated Cardiomyopathy and Limb-Girdle Muscular Dystrophy Type 2F via the SGCD Gene |
Citations
- Angelini, C., et.al. (1998). "Homozygous alpha-sarcoglycan mutation in two siblings: one asymptomatic and one steroid-responsive mild limb-girdle muscular dystrophy patient." Muscle Nerve 21(6): 769-75. PubMed ID: 9585331
- Carrie, A., et.al. (1997). "Mutational diversity and hot spots in the alpha-sarcoglycan gene in autosomal recessive muscular dystrophy (LGMD2D)." J Med Genet 34(6): 470-5. PubMed ID: 9192266
- Duggan DJ, Gorospe JR, Fanin M, Hoffman EP, Angelini C. 1997. Mutations in the sarcoglycan genes in patients with myopathy. N. Engl. J. Med. 336: 618-624. PubMed ID: 9032047
- Erynn Gordon, et.al. (2009). "Limb-Girdle Muscular Dystrophy Overview."
- Guglieri M, Bushby K. 2008. How to go about diagnosing and managing the limb-girdle muscular dystrophies. Neurology India 56:271-280. PubMed ID: 18974553
- Laval SH, Bushby KMD. 2004. Limb-girdle muscular dystrophies - from genetics to molecular pathology. Neuropathology and Applied Neurobiology 30: 91-105. PubMed ID: 15043707
- Mendell, J. R., et.al. (2010). "Sustained alpha-sarcoglycan gene expression after gene transfer in limb-girdle muscular dystrophy, type 2D." Ann Neurol 68(5): 629-38. PubMed ID: 21031578
- 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
- Roberds, S. L., et.al. (1994). "Missense mutations in the adhalin gene linked to autosomal recessive muscular dystrophy." Cell 78(4): 625-33. PubMed ID: 8069911
- 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
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Requisition Form
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- 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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