Glycogen storage disease type I diagnostic study of choice

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

Overview

Glycogen storage disease type 1 is diagnosed by identification of proband by either molecular genetic testing or enzyme activity assay.

Glycogen storage disease type 1 is diagnosed by identification of proband by either of the following:^[1]

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 GSD type I
Comprehensive genomic testing	Genome sequencing

Enzyme 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]
Enzyme activity assay performed are:
- Glucose-6-phosphatase (G6Pase) catalytic activity
- Glucose-6-phosphate exchanger SLC37A4 (transporter) activity

↑ 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/
↑ 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/
↑ 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.
↑ 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/