Glycogen Storage Disorders- Liver: Sequencing Panel

Condition Description

Glycogen storage disorders (GSDs) are a group of inherited genetic defects of glycogen metabolism. Most of them have autosomal recessive inheritance, however there are a few exceptions. There are more than 20 subtypes classified by the specific enzyme deficiency, affected tissue, and disease phenotype. Clinical and biochemical features continue to be used reliably to assign patients to this general disease category. Identification of the precise genetic defect is important, as molecular analysis is likely to expand the clinical spectrum of GSDs, may provide data relevant to prognosis and future therapeutic intervention and is important for carrier testing and early prenatal diagnosis.

The overall incidence of GSDs as a group is estimated to be 1 in 20,000-43,000 births. GSDs primarily affect the liver, the muscle, or both. Although the phenotype range is broad, the majority of clinical manifestations are hepatomegaly, failure to thrive, hypoglycemia, hyperlactatemia, hyperuricemia, and hyperlipidemia. The GSD - Liver Sequencing Panel covers 11 genes in which pathogenic variants cause a liver isoforms of GSD and disorders that have overlapping phenotype with GSDs.

References:
  • Burwinkel et al. (2005), Am J Hum Genet, 76:1034-1049.
  • Morris et al. (1995), J Inherit Metab Dis, 18:28-32.
  • Santer, Steinmamm, and Schaub. (2002), Curr Mol Med, 2:213-227.

Genes (11)

Your search may have returned a result for a gene alias. Click here for a full list of genes and their aliases.

Indications

This test is indicated for:
  • Confirmation of a clinical diagnosis of glycogen storage disorders (GSDs).
  • Carrier testing in adults with a family history of glycogen storage disorders (GSDs).

Methodology

Next Generation Sequencing: In-solution hybridization of all coding exons is performed on the patient's genomic DNA. Although some deep intronic regions may also be analyzed, this assay is not meant to interrogate most promoter regions, deep intronic regions, or other regulatory elements, and does not detect single or multi-exon deletions or duplications. Direct sequencing of the captured regions is performed using next generation sequencing. The patient's gene sequences are then compared to a standard reference sequence. Potentially causative variants and areas of low coverage are Sanger-sequenced. Sequence variations are classified as pathogenic, likely pathogenic, benign, likely benign, or variants of unknown significance. Variants of unknown significance may require further studies of the patient and/or family members.

Detection

Next Generation Sequencing: Clinical Sensitivity: Unknown. Mutations in the promoter region, some mutations in the introns and other regulatory element mutations cannot be detected by this analysis. Large deletions/duplications will not be detected by this analysis. Results of molecular analysis should be interpreted in the context of the patient\'s clinical/biochemical phenotype.

Analytical Sensitivity: ~99%.

Specimen Requirements

When sample fails to meet the acceptable criteria, please call 470.378.2200 and ask to speak with a laboratory genetic counselor (eglgc@egl-eurofins.com).
Submit only 1 of the following specimen types
Saliva
SLV

Requirements
Oragene™ Saliva Collection Kit
Orangene™ Saliva Collection Kit used according to manufacturer instructions. Please contact EGL for a Saliva Collection Kit for patients that cannot provide a blood sample.
Collection and Shipping
Please do not refrigerate or freeze saliva sample. Please store and ship at room temperature.
DNA, Isolated
DNA

Requirements
Microtainer
8µg
Isolation using the Perkin Elmer™Chemagen™ Chemagen™ Automated Extraction method or Qiagen™ Puregene kit for DNA extraction is recommended.
Collection and Shipping
Refrigerate until time of shipment in 100 ng/µL in TE buffer. Ship sample at room temperature with overnight delivery.
Whole Blood (EDTA)
WBP

Requirements
EDTA (Purple Top)
Infants and Young Children (<2 years of age): 2-3 ml
Children > 2 years of age to 10 years old: 3-5 ml
Older Children & Adults: 5-10 ml
Autopsy: 2-3 ml unclotted cord or cardiac blood
Collection and Shipping
Ship sample at room temperature for receipt at EGL within 24 hours of collection. Do not refrigerate or freeze.
  • Pompe (dry blood spot - test code DZ; leukocytes - DW).
  • Glycogen Storage Disorders- Liver: Deletion/Duplication Panel

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