Polyglucosan Body Myopathy Type I, with or without Immunodeficiency, via the RBCK1 Gene

Summary and Pricing

Test Method

Exome Sequencing with CNV Detection
Test Code Test Copy GenesTest CPT Code Gene CPT Codes Copy CPT Codes Base Price
8177 RBCK1 81479 81479,81479 $890 Order Options and Pricing
Test Code Test Copy Genes Test CPT Code Gene CPT Codes Copy CPT Code Base Price
8177RBCK181479 81479(x2) $890 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.

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 backbone).

Click here for costs to reflex to whole PGnome (if original test is on PGnome Sequencing backbone).

The Sanger Sequencing method for this test is NY State approved.

For Sanger Sequencing click here.

Turnaround Time

18 days on average for standard orders or 13 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

Polyglucosan body myopathy type I is caused by a genetic deficiency of the ubiquitin ligase RBCK1. The majority of patients that have been described to date have presented with progressive muscle weakness that typically begins with leg weakness, dilated cardiomyopathy, and polyglucosan accumulation in the skeletal muscle, heart, and/or liver. Some of these patients have also presented with ptosis, scoliosis, hepatomegaly, elevated liver transaminases, and growth retardation. Onset is typically during childhood or adolescence (Nilsson et al. 2013; Wang et al. 2013).

A small number of more severely affected patients have been reported. These patients have presented with severe immune dysfunction, including B-cell memory deficiency and hyper-IgA syndrome. As a result, they suffered frequent bacteriological infections from infancy and throughout childhood, chronic systemic inflammation, gastrointestinal symptoms (including vomiting, diarrhea, abdominal pain, and blood and mucous in stools), and dermatological abnormalities. RBCK1 deficiency was fatal in all three of the patients described with this more severe presentation (Boisson et al. 2012).

Genetics

Polyglucosan body myopathy type I is an autosomal recessive disorder caused by pathogenic variants in the RBCK1 gene. Over 10 pathogenic variants have been described in this gene. The majority of reported variants are expected to lead to premature protein termination, and include nonsense variants, small frameshift deletions and insertions, and splice variants. A small number of missense variants have been reported, as well as one multi-exonic deletion (Human Gene Mutation Database). It has been proposed that the severity of the phenotype may be related to the type and location of sequence variant within RBCK1. For example, patients with a missense variant tend to have a mild form of disease with either no cardiomyopathy, or later-onset cardiomyopathy. The small number of patients with immunological symptoms have had loss-of-function variants that reside within the N-terminal region of RBCK1, whereas the patients without immunological symptoms have had at least one variant located in the middle or C-terminal region of RBCK1 (Nilsson et al. 2013).

The RBCK1 gene encodes an E3 ubiquitin ligase. It interacts with a variety of different proteins, including EYA1 (involved in myogenesis) and IRP2 (involved in control of iron homeostasis). It is also part of the linear ubiquitin assembly complex (LUBAC), which is important for regulation of the NFkB pathway that plays an important role in regulation of the immune system (Nilsson et al. 2013).

Clinical Sensitivity - Sequencing with CNV PGxome

Based on cumulative totals of patients reported in the literature, 29 small sequence variants were detected in a total of 16 patients, for an estimated sensitivity of ~91% (29 of 32 alleles). The remaining 3 alleles were multi-exonic deletions that would not be expected to be detected via direct sequencing (Boisson et al. 2012; Nilsson et al. 2013; Wang et al. 2013).

Testing Strategy

This test provides full coverage of all coding exons of the RBCK1 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

Patients with clinical features consistent with polyglucosan body myopathy type I, with or without immunodeficiency, are good candidates for this test. Family members of patients who have known RBCK1 pathogenic variants are also good candidates. We will also sequence the RBCK1 gene to determine carrier status.

Gene

Official Gene Symbol OMIM ID
RBCK1 610924
Inheritance Abbreviation
Autosomal Dominant AD
Autosomal Recessive AR
X-Linked XL
Mitochondrial MT

Citations

  • Boisson B. et al. 2012. Nature Immunology. 13: 1178-86. PubMed ID: 23104095
  • Human Gene Mutation Database (Bio-base).
  • Nilsson J. et al. 2013. Annals of Neurology. 74: 914-9. PubMed ID: 23798481
  • Wang K. et al. 2013. Genome Medicine. 5: 67. PubMed ID: 23889995

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

PGxome (Exome) Sequencing Panel

PGnome (Genome) Sequencing Panel

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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.
Total Price: $
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