Glycogen storage disease type I other diagnostic studies: Difference between revisions

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==Other Diagnostic Studies==
==Other Diagnostic Studies==
The diagnosis is definitively confirmed by liver [[biopsy]] with [[electron microscopy]] and [[assay]] of [[glucose-6-phosphatase]] activity in the tissue and/or specific gene testing, available in recent years.
GSD type 1 is diagnosed by identification of proband by either of the following:<ref>Bali DS, Chen YT, Austin S, et al. Glycogen Storage Disease Type I. 2006 Apr 19 [Updated 2016 Aug 25]. In: Adam MP, Ardinger HH, Pagon RA, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2017. Available from: https://www.ncbi.nlm.nih.gov/books/NBK1312/
</ref>
* Molecular genetic testing
* Enzyme Activity Assay


[[Prenatal diagnosis]] has been made by fetal [[liver biopsy]] at 18-22 weeks of gestation, but no fetal treatment has been proposed. Prenatal diagnosis is possible with fetal [[DNA]] obtained by [[chorionic villus sampling]] when a fetus is known to be at risk.
===Molecular genetic testing===
*Molecular genetic testing shows:<ref>Bali DS, Chen YT, Austin S, et al. Glycogen Storage Disease Type I. 2006 Apr 19 [Updated 2016 Aug 25]. In: Adam MP, Ardinger HH, Pagon RA, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2017. Available from: https://www.ncbi.nlm.nih.gov/books/NBK1312/
</ref>
**Biallelic pathogenic variants in G6PC for patients with GSD type 1a
**Biallelic pathogenic variants in SLC37A4 for patients with GSD type 1b
 
{|
! colspan="3" style="background:#4479BA; color: #FFFFFF;" align="center" + |Molecular genetic testing
|-
! colspan="2" style="background:#4479BA; color: #FFFFFF;" align="center" + |Genetic testing
! style="background:#4479BA; color: #FFFFFF;" align="center" + |Analysis performed
|-
| colspan="2" style="background:#DCDCDC;" align="center" + |Serial single-gene testing
| style="background:#F5F5F5;" + |
*First sequence analysis of G6PC is done
*sequence analysis of SLC37A4 if no G6PC pathogenic variants identified
|-
| colspan="2" style="background:#DCDCDC;" align="center" + |Targeted analysis
| style="background:#F5F5F5;" + |
*For G6PC pathogenic variant
** Ashkenazi Jewish ancestry<ref name="pmid15316959">{{cite journal| author=Ekstein J, Rubin BY, Anderson SL, Weinstein DA, Bach G, Abeliovich D et al.| title=Mutation frequencies for glycogen storage disease Ia in the Ashkenazi Jewish population. | journal=Am J Med Genet A | year= 2004 | volume= 129A | issue= 2 | pages= 162-4 | pmid=15316959 | doi=10.1002/ajmg.a.30232 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=15316959  }} </ref>
*** p.Arg83Cys analysis
*For G6PD pathogenic variant
** Old Order Amish ancestry
*** p.Gln347Ter analysis
|-
| colspan="2" style="background:#DCDCDC;" align="center" + |Multigene panel
| style="background:#F5F5F5;" + |
*Multiple genes are sequenced at the same time including  G6PC, SLC37A4 and other related genes when differential diagnosis is considered
|-
| rowspan="2" style="background:#DCDCDC;" align="center" + |Comprehensive genomic testing
| style="background:#DCDCDC;" align="center" + |Exome sequencing
|rowspan="2" style="background:#F5F5F5;" + |
*Considered if the diagnosis is not confirmed by serial single-gene testing and/or use of a multigene panel in an individual with features of GSDI
|-
| style="background:#DCDCDC;" align="center" + |Genome sequencing
|}
 
*Molecular genetic testing is preferred over enzyme activity assay due to:
**Relatively high sensitivity
**Need for liver biopsy for enzyme activity assay
 
===Enzyme Activity Assay===
*Enzymatic activity assay is performed on frozen liver (ample of 15-20 mg) obtained by percutaneous or open liver biopsy. Transport should be done on dry ice via overnight delivery to the clinical diagnostic laboratory.<ref>Bali DS, Chen YT, Austin S, et al. Glycogen Storage Disease Type I. 2006 Apr 19 [Updated 2016 Aug 25]. In: Adam MP, Ardinger HH, Pagon RA, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2017. Available from: https://www.ncbi.nlm.nih.gov/books/NBK1312/
</ref>
*Enzymatic activity assay performed are:
**Glucose-6-phosphatase (G6Pase) catalytic activity
**Glucose-6-phosphate exchanger SLC37A4 (transporter) activity


==References==
==References==

Revision as of 16:59, 21 November 2017

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief:

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Overview

Other Diagnostic Studies

GSD type 1 is diagnosed by identification of proband by either of the following:[1]

  • Molecular genetic testing
  • Enzyme Activity Assay

Molecular genetic testing

  • Molecular genetic testing shows:[2]
    • Biallelic pathogenic variants in G6PC for patients with GSD type 1a
    • Biallelic pathogenic variants in SLC37A4 for patients with GSD type 1b
Molecular genetic testing
Genetic testing Analysis performed
Serial single-gene testing
  • First sequence analysis of G6PC is done
  • sequence analysis of SLC37A4 if no G6PC pathogenic variants identified
Targeted analysis
  • For G6PC pathogenic variant
    • Ashkenazi Jewish ancestry[3]
      • p.Arg83Cys analysis
  • For G6PD pathogenic variant
    • Old Order Amish ancestry
      • p.Gln347Ter analysis
Multigene panel
  • Multiple genes are sequenced at the same time including G6PC, SLC37A4 and other related genes when differential diagnosis is considered
Comprehensive genomic testing Exome sequencing
  • Considered if the diagnosis is not confirmed by serial single-gene testing and/or use of a multigene panel in an individual with features of GSDI
Genome sequencing
  • Molecular genetic testing is preferred over enzyme activity assay due to:
    • Relatively high sensitivity
    • Need for liver biopsy for enzyme activity assay

Enzyme Activity Assay

  • Enzymatic activity assay is performed on frozen liver (ample of 15-20 mg) obtained by percutaneous or open liver biopsy. Transport should be done on dry ice via overnight delivery to the clinical diagnostic laboratory.[4]
  • Enzymatic activity assay performed are:
    • Glucose-6-phosphatase (G6Pase) catalytic activity
    • Glucose-6-phosphate exchanger SLC37A4 (transporter) activity

References

  1. ↑ Bali DS, Chen YT, Austin S, et al. Glycogen Storage Disease Type I. 2006 Apr 19 [Updated 2016 Aug 25]. In: Adam MP, Ardinger HH, Pagon RA, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2017. Available from: https://www.ncbi.nlm.nih.gov/books/NBK1312/
  2. ↑ Bali DS, Chen YT, Austin S, et al. Glycogen Storage Disease Type I. 2006 Apr 19 [Updated 2016 Aug 25]. In: Adam MP, Ardinger HH, Pagon RA, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2017. Available from: https://www.ncbi.nlm.nih.gov/books/NBK1312/
  3. ↑ Ekstein J, Rubin BY, Anderson SL, Weinstein DA, Bach G, Abeliovich D; et al. (2004). "Mutation frequencies for glycogen storage disease Ia in the Ashkenazi Jewish population". Am J Med Genet A. 129A (2): 162–4. doi:10.1002/ajmg.a.30232. PMID 15316959.
  4. ↑ Bali DS, Chen YT, Austin S, et al. Glycogen Storage Disease Type I. 2006 Apr 19 [Updated 2016 Aug 25]. In: Adam MP, Ardinger HH, Pagon RA, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2017. Available from: https://www.ncbi.nlm.nih.gov/books/NBK1312/

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