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World J Gastroenterol. Jul 7, 2023; 29(25): 3932-3963
Published online Jul 7, 2023. doi: 10.3748/wjg.v29.i25.3932
Glycogen storage diseases: An update
Ersin Gümüş, Hasan Özen
Ersin Gümüş, Hasan Özen, Department of Pediatric Gastroenterology, Hepatology and Nutrition, Hacettepe University Faculty of Medicine, Ihsan Dogramaci Children’s Hospital, Ankara 06230, Turkey
Author contributions: Both authors contributed all parts of the study.
Conflict-of-interest statement: All the authors report no relevant conflicts of interest for this article.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:
Corresponding author: Hasan Özen, MD, Professor, Department of Pediatric Gastroenterology, Hepatology and Nutrition, Hacettepe University Faculty of Medicine, Ihsan Dogramaci Children’s Hospital, Gevher Nesibe Cad., Ankara 06230, Turkey.
Received: December 28, 2022
Peer-review started: December 28, 2022
First decision: February 1, 2023
Revised: February 15, 2023
Accepted: April 30, 2023
Article in press: April 30, 2023
Published online: July 7, 2023

Glycogen storage diseases (GSDs), also referred to as glycogenoses, are inherited metabolic disorders of glycogen metabolism caused by deficiency of enzymes or transporters involved in the synthesis or degradation of glycogen leading to aberrant storage and/or utilization. The overall estimated GSD incidence is 1 case per 20000-43000 live births. There are over 20 types of GSD including the subtypes. This heterogeneous group of rare diseases represents inborn errors of carbohydrate metabolism and are classified based on the deficient enzyme and affected tissues. GSDs primarily affect liver or muscle or both as glycogen is particularly abundant in these tissues. However, besides liver and skeletal muscle, depending on the affected enzyme and its expression in various tissues, multiorgan involvement including heart, kidney and/or brain may be seen. Although GSDs share similar clinical features to some extent, there is a wide spectrum of clinical phenotypes. Currently, the goal of treatment is to maintain glucose homeostasis by dietary management and the use of uncooked cornstarch. In addition to nutritional interventions, pharmacological treatment, physical and supportive therapies, enzyme replacement therapy (ERT) and organ transplantation are other treatment approaches for both disease manifestations and long-term complications. The lack of a specific therapy for GSDs has prompted efforts to develop new treatment strategies like gene therapy. Since early diagnosis and aggressive treatment are related to better prognosis, physicians should be aware of these conditions and include GSDs in the differential diagnosis of patients with relevant manifestations including fasting hypoglycemia, hepatomegaly, hypertransaminasemia, hyperlipidemia, exercise intolerance, muscle cramps/pain, rhabdomyolysis, and muscle weakness. Here, we aim to provide a comprehensive review of GSDs. This review provides general characteristics of all types of GSDs with a focus on those with liver involvement.

Keywords: Glycogen storage disease, Liver, Muscle, Hypoglycemia

Core Tip: Glycogen storage diseases are multisystemic diseases that can present at any age. Primarily affected organs are liver and skeletal muscle, but heart, central nervous system, kidneys, intestines, and other organs may also be affected. As the initial presenting symptoms can occur in adulthood, it is a group of rare diseases that should be recognized and managed by not only pediatricians but also physicians taking care of adults.