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Merosin-Deficient Congenital Muscular Dystrophy (MDC1A) via the LAMA2 Gene, Exon 55

Summary and Pricing

Test Method

Bi-Directional Sanger Sequencing
Test Code Test Copy GenesTest CPT Code Gene CPT Codes Copy CPT Codes Base Price
245 LAMA2 81403 81403 $250 Order Options and Pricing
Test Code Test Copy Genes Test CPT Code Gene CPT Codes Copy CPT Code Base Price
245LAMA281403 81403 $250 Order Options and Pricing

Pricing Comments

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.

Turnaround Time

12 days on average for standard orders or 8 days 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.

EMAIL CONTACTS

Genetic Counselors

Geneticist

  • Angela Gruber, PhD

Clinical Features and Genetics

Clinical Features

Merosin-deficient congenital muscular dystrophy (MDC1A; OMIM 607855) is characterized clinically by muscle weakness, delayed motor milestones, white matter changes, mental retardation, hypotonia, and seizures (Philpot et al. Neuromusc Disord 9:81-85, 1999). However, notable variation in phenotypic severity, age of onset, and disease progression has been reported (Jones et al. J Med Genet 38: 649-657, 2001). Muscle histology includes dystrophic features and adipose infiltration, but other findings typical of Duchenne biopsies are less apparent (Taniguchi et al. Biochem Biophys Res Commun 342: 489-502, 2006).

Genetics

The LAMA2 gene codes for the α-2 subunit of LAMININ-2 (merosin), the main laminin of muscle tissue. MDC1A is inherited as an autosomal recessive disorder. Variants are distributed throughout the coding region, and some genotype-phenotype correlations have been made (http://www.dmd.nl/; Muntoni and Voit, Neuromuscul Disord 14:635-49, 2004). An exon 55 nonsense variant (c.7732C>T; p.Arg2578*) has been found as a recurring cause of MDC1A in individuals with Mexican ancestry (Coral-Vazquez et al. J Hum Genet 48:91-95, 2003).

Clinical Sensitivity - Sanger Sequencing

Merosin-deficient CMD is thought to account for ~50% of all CMD. Because CMD demonstrates extensive locus and allelic heterogeneity, a negative LAMA2 sequence result does not rule out a diagnosis of this disorder when classic clinical findings are present. If a muscle biopsy is available, immunostaining may also be an appropriate diagnostic approach. Most patients with partial merosin deficiency do not have LAMA2 variants (Tezak et al., Hum Mutat 21:103-11, 2003). In these cases, evaluation of other CMD genes may be a reasonable diagnostic approach.

Testing Strategy

The α-2 subunit of LAMININ-2 is coded by exons 1-65 of the LAMA2 gene located on chromosome 6q22-q23. Testing is accomplished by amplifying exon 55 and ~10 bp of adjacent noncoding sequence, then determining the nucleotide sequence using standard dideoxy sequencing methods and capillary electrophoresis.

Indications for Test

Individuals of Mexican origin with symptoms consistent with CMD. Individuals with immunofluorescence results demonstrating complete merosin deficiency.

Gene

Official Gene Symbol OMIM ID
LAMA2 156225
Inheritance Abbreviation
Autosomal Dominant AD
Autosomal Recessive AR
X-Linked XL
Mitochondrial MT

Disease

Name Inheritance OMIM ID
Merosin Deficient Congenital Muscular Dystrophy AR 607855

Citations

  • Coral-Vazquez RM, Rosas-Vargas H, Meza-Espinosa P, Mendoza I, Huicochea JC, Ramon G, Salamanca F. 2003. Severe congenital muscular dystrophy in a Mexican family with a new nonsense mutation (R2578X) in the laminin α-2 gene. Journal of human genetics 48: 0091–0095. PubMed ID: 12601554
  • Jones KJ, Morgan G, Johnston H, Tobias V, Ouvrier RA, Wilkinson I, North KN. 2001. The expanding phenotype of laminin alpha2 chain (merosin) abnormalities: case series and review. J. Med. Genet. 38: 649–657. PubMed ID: 11584042
  • Leiden Muscular Dystrophy pages..
  • Muntoni F, Voit T. 2004. The congenital muscular dystrophies in 2004: a century of exciting progress. Neuromuscul. Disord. 14: 635–649. PubMed ID: 15351421
  • Philpot J, Cowan F, Pennock J, Sewry C, Dubowitz V, Bydder G, Muntoni F. 1999. Merosin-deficient congenital muscular dystrophy: the spectrum of brain involvement on magnetic resonance imaging. Neuromuscul. Disord. 9: 81–85. PubMed ID: 10220862
  • Taniguchi M, Kurahashi H, Noguchi S, Sese J, Okinaga T, Tsukahara T, Guicheney P, Ozono K, Nishino I, Morishita S, Toda T. 2006. Expression profiling of muscles from Fukuyama-type congenital muscular dystrophy and laminin-alpha 2 deficient congenital muscular dystrophy; is congenital muscular dystrophy a primary fibrotic disease? Biochem. Biophys. Res. Commun. 342: 489–502. PubMed ID: 16487936
  • Tezak, Z., et.al. (2003). "Clinical and molecular study in congenital muscular dystrophy with partial laminin alpha 2 (LAMA2) deficiency." Hum Mutat 21(2): 103-11. PubMed ID: 12552556

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


Specimen Types

Specimen Requirements and Shipping Details

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ORDER OPTIONS

View Ordering Instructions

1) Select Test Method (Backbone)


1) Select Test Type


2) Select Additional Test Options

STAT and Prenatal Test Options are not available with Patient Plus.

No Additional Test Options are available for this test.

Note: acceptable specimen types are whole blood and DNA from whole blood only.
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