Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Review

Glycogen Storage Disease Type VI

Emma Labrador  1 , David A Weinstein  2
Margaret P Adam, Jerry Feldman, Ghayda M Mirzaa, Roberta A Pagon, Stephanie E Wallace, Anne Amemiya
, editors.
In: GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993.
[updated ].
Affiliations
Free Books & Documents
Review

Glycogen Storage Disease Type VI

Emma Labrador et al.
Free Books & Documents

Excerpt

Clinical characteristics: Glycogen storage disease type VI (GSD VI) is a disorder of glycogenolysis caused by deficiency of hepatic glycogen phosphorylase. This critical enzyme catalyzes the rate-limiting step in glycogen degradation, and deficiency of the enzyme in the untreated child is characterized by hepatomegaly, poor growth, ketotic hypoglycemia, elevated hepatic transaminases, hyperlipidemia, and low prealbumin level. GSD VI is usually a relatively mild disorder that presents in infancy and childhood; rare cases of more severe disease manifesting with recurrent hypoglycemia and marked hepatomegaly have been described. More common complications in the setting of suboptimal metabolic control include short stature, delayed puberty, osteopenia, and osteoporosis. Hepatic fibrosis commonly develops in GSD VI, but cirrhosis and hypertrophic cardiomyopathy are rare. Clinical and biochemical abnormalities may decrease with age, but ketosis and hypoglycemia can continue to occur.

Diagnosis/testing: The diagnosis of GSD VI is established in a proband with typical clinical findings and/or biallelic pathogenic variants in PYGL identified by molecular genetic testing.

Management: Treatment of manifestations: Some individuals with GSD VI may not require any treatment, but treatment with cornstarch and protein improves growth, stamina, and ameliorates biochemical abnormalities including hypoglycemia and ketosis. Even in those with no hypoglycemia, a bedtime dose of cornstarch improves energy and prevents ketosis.

Surveillance: Monitoring of blood glucose and blood ketone levels at least several times per month during times of stress including illness, intense activity, periods of rapid growth, or any time at which intake of food is reduced. Annual liver ultrasound examinations should start at age five years. Bone density exam is recommended when puberty is complete.

Agents/circumstances to avoid: Excessive amounts of simple sugars; glucagon administration as a rescue therapy for hypoglycemia; growth hormone therapy for short stature; contact sports when hepatomegaly is present.

Evaluation of relatives at risk: If the family-specific pathogenic variants are known, it is appropriate to offer molecular genetic testing to at-risk sibs so that early treatment and avoidance of factors that exacerbate disease can be initiated.

Genetic counseling: GSD VI is inherited in an autosomal recessive manner. At conception, each sib of an affected individual has a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier. Carrier testing for at-risk relatives and prenatal diagnosis for pregnancies at increased risk are possible if the pathogenic variants in the family are known.

PubMed Disclaimer

Similar articles

  • Glycogen Storage Disease Type III.
    Schreuder AB, Rossi A, Grünert SC, Derks TGJ. Schreuder AB, et al. 2010 Mar 9 [updated 2022 Jan 6]. In: Adam MP, Feldman J, Mirzaa GM, Pagon RA, Wallace SE, Amemiya A, editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993–2025. 2010 Mar 9 [updated 2022 Jan 6]. In: Adam MP, Feldman J, Mirzaa GM, Pagon RA, Wallace SE, Amemiya A, editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993–2025. PMID: 20301788 Free Books & Documents. Review.
  • Phosphorylase Kinase Deficiency.
    Herbert M, Goldstein JL, Rehder C, Austin S, Kishnani PS, Bali DS. Herbert M, et al. 2011 May 31 [updated 2018 Nov 1]. In: Adam MP, Feldman J, Mirzaa GM, Pagon RA, Wallace SE, Amemiya A, editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993–2025. 2011 May 31 [updated 2018 Nov 1]. In: Adam MP, Feldman J, Mirzaa GM, Pagon RA, Wallace SE, Amemiya A, editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993–2025. PMID: 21634085 Free Books & Documents. Review.
  • Glycogen Storage Disease Type I.
    Bali DS, El-Gharbawy A, Austin S, Pendyal S, Kishnani PS. Bali DS, et al. 2006 Apr 19 [updated 2021 Oct 14]. In: Adam MP, Feldman J, Mirzaa GM, Pagon RA, Wallace SE, Amemiya A, editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993–2025. 2006 Apr 19 [updated 2021 Oct 14]. In: Adam MP, Feldman J, Mirzaa GM, Pagon RA, Wallace SE, Amemiya A, editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993–2025. PMID: 20301489 Free Books & Documents. Review.
  • Glycogen Storage Disease Type IV.
    Magoulas PL, El-Hattab AW. Magoulas PL, et al. 2013 Jan 3 [updated 2019 Aug 1]. In: Adam MP, Feldman J, Mirzaa GM, Pagon RA, Wallace SE, Amemiya A, editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993–2025. 2013 Jan 3 [updated 2019 Aug 1]. In: Adam MP, Feldman J, Mirzaa GM, Pagon RA, Wallace SE, Amemiya A, editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993–2025. PMID: 23285490 Free Books & Documents. Review.
  • Citrullinemia Type I.
    Quinonez SC, Lee KN. Quinonez SC, et al. 2004 Jul 7 [updated 2022 Aug 18]. In: Adam MP, Feldman J, Mirzaa GM, Pagon RA, Wallace SE, Amemiya A, editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993–2025. 2004 Jul 7 [updated 2022 Aug 18]. In: Adam MP, Feldman J, Mirzaa GM, Pagon RA, Wallace SE, Amemiya A, editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993–2025. PMID: 20301631 Free Books & Documents. Review.
See all similar articles

References

    1. Beauchamp NJ, Taybert J, Champion MP, Layet V, Heinz-Erian P, Dalton A, Tanner MS, Pronicka E, Sharrard MJ. High frequency of missense mutations in glycogen storage disease type VI. J Inherit Metab Dis. 2007;30:722–34. - PubMed
    1. Burwinkel B, Bakker HD, Herschkovitz E, Moses SW, Shin YS, Kilimann MW. Mutations in the liver glycogen phosphorylase gene (PYGL) underlying glycogenosis type VI. Am J Hum Genet. 1998;62:785–91. - PMC - PubMed
    1. Chang S, Rosenberg MJ, Morton H, Francomano CA, Biesecker LG. Identification of a mutation in liver glycogen phosphorylase in glycogen storage disease type VI. Hum Mol Genet. 1998;7:865–70. - PubMed
    1. Chen MA, Weinstein DA. Glycogen storage diseases: diagnosis, treatment, and outcome. Transl Sci Rare Dis. 2016;1:45–72. Available online. Accessed 5-10-23.
    1. Hers HG. Rev Int Hepatol. 1959;9:35–55. [Enzymatic studies of hepatic fragments; application to the classification of glycogenoses.] - PubMed

LinkOut - more resources