Nutrition Management in Children Less than 5 Years of Age with Glycogen Storage Disease Type I: Survey Results.

Background: Nutrition management for GSD Type I (GSDI; OMIM #232200, 232220) is complex, with the goal being to maintain euglycemia while minimizing metabolic derangements. Management guidelines were published in 2002 and 2014. However, there is limited information on the nuances of nutrition management and the unique feeding challenges of children. Methods: A REDCap survey focusing on staffing and current practices in the nutrition management of children with GSD I who were <5 years of age was sent to the metabolic dietitian's listserv and GMDI membership in 8/2023. Results: There were 21 North American respondents. In 17/21 clinics (81%), Prosobee® was the primary choice for infant formula. Dietitians used different methods to determine hourly glucose needs. Fasting recommendations ranged from 1 to 3 h, and the use of nighttime continuous feeding was common. Cornstarch was started between 6 and 12 months of age. Most clinics did not use Glycosade® for children <5 years of age. Oral motor dysfunction, gagging, and lack of interest in food were common. Continuous glucose monitoring (CGM) devices were recommended in 20 clinics (95%). Most clinics followed patients on an outpatient basis. All clinics provided a hypoglycemia management plan; however, there was wide variability in practice. Conclusion: This survey highlights the variability in the care of individuals <5 years of age with GSD I. Updated guidelines are needed to help address the unique nutrition challenges in this age group.

The interplay of psychosis and non-compliance with fatal outcome in an adult with MSUD.

Significant progress has been achieved in enhancing early outcomes for individuals with maple syrup urine disease (MSUD), a rare metabolic disorder that leads to the accumulation of branched-chain amino acids leucine, isoleucine, and valine, where leucine is known as the primary neurotoxic metabolite. Newborn screening is helpful in early diagnosis and implementation of dietary treatment, thus reducing neurological deterioration and complications in young children. However, patients face the life-long challenge of maintaining metabolic control through adherence to a strict low-leucine diet to avoid long-term consequences of chronic hyperleucinemia, which include cognitive deficits, mood disorders, and movement disorders. This case report exemplifies the complex involvement of MSUD in adult survivors. Despite presenting early in life, the patient thrived until the onset of psychiatric symptoms. The subject of this case is a 25-year-old woman with MSUD, who remained in her usual state of health until presentation to the emergency department (ED) with psychosis and altered mental status. However, due to a lack of medical records and poor communication, there was a delay in considering MSUD as a primary cause of her psychiatric symptoms. Although a genetics consultation was later arranged and efforts were made to decrease plasma leucine to the therapeutic range, these interventions proved inadequate in halting her deterioration in health. Her condition worsened within 72 h, culminating in her untimely death. This case emphasizes the comorbidity of psychiatric involvement in MSUD, which contributes to metabolic decompensation that can lead to cerebral edema and death. This case also highlights the pressing need for enhanced strategies for the acute management and long-term care of MSUD patients with psychiatric involvement, particularly in scenarios where mental disturbance could lead to noncompliance.

Treatment recommendations for glycogen storage disease type IB- associated neutropenia and neutrophil dysfunction with empagliflozin: Consensus from an international workshop.

Glycogen storage disease type Ib (GSD Ib, biallelic variants in SLC37A4) is a rare disorder of glycogen metabolism complicated by neutropenia/neutrophil dysfunction. Since 2019, the SGLT2-inhibitor empagliflozin has provided a mechanism-based treatment option for the symptoms caused by neutropenia/neutrophil dysfunction (e.g. mucosal lesions, inflammatory bowel disease). Because of the rarity of GSD Ib, the published evidence on safety and efficacy of empagliflozin is still limited and does not allow to develop evidence-based guidelines. Here, an international group of experts provides 14 best practice consensus treatment recommendations based on expert practice and review of the published evidence. We recommend to start empagliflozin in all GSD Ib individuals with clinical or laboratory signs related to neutropenia/neutrophil dysfunction with a dose of 0.3-0.4 mg/kg/d given as a single dose in the morning. Treatment can be started in an outpatient setting. The dose should be adapted to the weight and in case of inadequate clinical treatment response or side effects. We strongly recommend to pause empagliflozin immediately in case of threatening dehydration and before planned longer surgeries. Discontinuation of G-CSF therapy should be attempted in all individuals. If available, 1,5-AG should be monitored. Individuals who have previously not tolerated starches should be encouraged to make a new attempt to introduce starch in their diet after initiation of empagliflozin treatment. We advise to monitor certain safety and efficacy parameters and recommend continuous, alternatively frequent glucose measurements during the introduction of empagliflozin. We provide specific recommendations for special circumstances like pregnancy and liver transplantation.

Development of hepatocellular adenomas in a patient with glycogen storage disease Ia treated with growth hormone therapy.

Glycogen storage disease Ia (GSD Ia), also known as von Gierke disease, is caused by pathogenic variants in the G6PC1 gene (OMIM 232200) which encodes glucose-6-phosphatase. Deficiency of glucose-6-phosphatase impairs the processes of gluconeogenesis and glycogenolysis by preventing conversion of glucose-6-phosphate to glucose. Clinical features include fasting hypoglycemia, lactic acidosis, hypertriglyceridemia, hyperuricemia, hepatomegaly, and development of hepatocellular adenomas (HCAs) with potential for malignant transformation. Additionally, patients with GSD Ia often exhibit short stature, in some instances due to growth hormone (GH) deficiency. Patients with short stature caused by GH deficiency typically receive GH injections. Here, we review the literature and describe a female with GSD Ia who had short stature, failure of growth progression, and suspected GH deficiency. This patient received GH injections from ages 11 to 14 years under careful monitoring of an endocrinologist and developed HCAs during that time. To date, there is no reported long-term follow up data on patients with GSD Ia who have received GH therapy, and therefore the clinical outcomes post-GH therapy are unclear.

Diagnosis and management of glycogen storage disease type IV, including adult polyglucosan body disease: A clinical practice resource.

Glycogen storage disease type IV (GSD IV) is an ultra-rare autosomal recessive disorder caused by pathogenic variants in GBE1 which results in reduced or deficient glycogen branching enzyme activity. Consequently, glycogen synthesis is impaired and leads to accumulation of poorly branched glycogen known as polyglucosan. GSD IV is characterized by a remarkable degree of phenotypic heterogeneity with presentations in utero, during infancy, early childhood, adolescence, or middle to late adulthood. The clinical continuum encompasses hepatic, cardiac, muscular, and neurologic manifestations that range in severity. The adult-onset form of GSD IV, referred to as adult polyglucosan body disease (APBD), is a neurodegenerative disease characterized by neurogenic bladder, spastic paraparesis, and peripheral neuropathy. There are currently no consensus guidelines for the diagnosis and management of these patients, resulting in high rates of misdiagnosis, delayed diagnosis, and lack of standardized clinical care. To address this, a group of experts from the United States developed a set of recommendations for the diagnosis and management of all clinical phenotypes of GSD IV, including APBD, to support clinicians and caregivers who provide long-term care for individuals with GSD IV. The educational resource includes practical steps to confirm a GSD IV diagnosis and best practices for medical management, including (a) imaging of the liver, heart, skeletal muscle, brain, and spine, (b) functional and neuromusculoskeletal assessments, (c) laboratory investigations, (d) liver and heart transplantation, and (e) long-term follow-up care. Remaining knowledge gaps are detailed to emphasize areas for improvement and future research.

Clinical insights from Wolman disease: Evaluating infantile hepatosplenomegaly.

There is a broad differential diagnosis of infantile hepatosplenomegaly, with some etiologies being debilitating and treatable. A structured approach to history, examination, and laboratory and radiographic findings is important in diagnosis. Herein, we present a case of Wolman disease presenting as hepatosplenomegaly in an infant. This case details important learning points to help distinguish the diagnosis of Wolman disease from other conditions with overlapping clinical features, such as hemophagocytic lymphohistiocytosis (HLH). The advent of enzyme replacement therapy has dramatically changed the natural history of Wolman disease, and this child showed remarkable improvement with treatment. This child was later found to have extensive adenopathy with retroperitoneal lymph node biopsy demonstrating diffuse infiltration by lipid-laden macrophages, fatty deposits, cholesterol crystals, and calcifications. Similar to the collection of characteristic cells in other lysosomal storage disorders, we postulate that this is characteristic of underlying Wolman disease. We conclude with a summary of learning points from this presentation on infantile hepatosplenomegaly, pertinent to the geneticist, pediatrician, and pediatric subspecialists.

Very early-onset inflammatory bowel disease: Novel description in glycogen storage disease type Ia.

Although inflammatory bowel disease is a well-described feature of glycogen storage disease type Ib, it has been reported in only a small number of individuals with glycogen storage disease type Ia (GSDIa). We describe, to our knowledge, the first patient with GSDIa and very early-onset inflammatory bowel disease (VEO-IBD). Larger studies are needed to better understand this possible association, elucidate the mechanism of VEO-IBD in GSDIa, and inform management.

A retrospective longitudinal study and comprehensive review of adult patients with glycogen storage disease type III.

INTRODUCTION: A deficiency of glycogen debrancher enzyme in patients with glycogen storage disease type III (GSD III) manifests with hepatic, cardiac, and muscle involvement in the most common subtype (type a), or with only hepatic involvement in patients with GSD IIIb. OBJECTIVE AND METHODS: To describe longitudinal biochemical, radiological, muscle strength and ambulation, liver histopathological findings, and clinical outcomes in adults (≥18 years) with glycogen storage disease type III, by a retrospective review of medical records. RESULTS: Twenty-one adults with GSD IIIa (14 F & 7 M) and four with GSD IIIb (1 F & 3 M) were included in this natural history study. At the most recent visit, the median (range) age and follow-up time were 36 (19-68) and 16 years (0-41), respectively. For the entire cohort: 40% had documented hypoglycemic episodes in adulthood; hepatomegaly and cirrhosis were the most common radiological findings; and 28% developed decompensated liver disease and portal hypertension, the latter being more prevalent in older patients. In the GSD IIIa group, muscle weakness was a major feature, noted in 89% of the GSD IIIa cohort, a third of whom depended on a wheelchair or an assistive walking device. Older individuals tended to show more severe muscle weakness and mobility limitations, compared with younger adults. Asymptomatic left ventricular hypertrophy (LVH) was the most common cardiac manifestation, present in 43%. Symptomatic cardiomyopathy and reduced ejection fraction was evident in 10%. Finally, a urinary biomarker of glycogen storage (Glc4) was significantly associated with AST, ALT and CK. CONCLUSION: GSD III is a multisystem disorder in which a multidisciplinary approach with regular clinical, biochemical, radiological and functional (physical therapy assessment) follow-up is required. Despite dietary modification, hepatic and myopathic disease progression is evident in adults, with muscle weakness as the major cause of morbidity. Consequently, definitive therapies that address the underlying cause of the disease to correct both liver and muscle are needed.

Dietary lipids in glycogen storage disease type III: A systematic literature study, case studies, and future recommendations.

A potential role of dietary lipids in the management of hepatic glycogen storage diseases (GSDs) has been proposed, but no consensus on management guidelines exists. The aim of this study was to describe current experiences with dietary lipid manipulations in hepatic GSD patients. An international study was set up to identify published and unpublished cases describing hepatic GSD patients with a dietary lipid manipulation. A literature search was performed according to the Cochrane Collaboration methodology through PubMed and EMBASE (up to December 2018). All delegates who attended the dietetics session at the IGSD2017, Groningen were invited to share unpublished cases. Due to multiple biases, only data on GSDIII were presented. A total of 28 cases with GSDIII and a dietary lipid manipulation were identified. Main indications were cardiomyopathy and/or myopathy. A high fat diet was the most common dietary lipid manipulation. A decline in creatine kinase concentrations (n = 19, P < .001) and a decrease in cardiac hypertrophy in paediatric GSDIIIa patients (n = 7, P < .01) were observed after the introduction with a high fat diet. This study presents an international cohort of GSDIII patients with different dietary lipid manipulations. High fat diet may be beneficial in paediatric GSDIIIa patients with cardiac hypertrophy, but careful long-term monitoring for potential complications is warranted, such as growth restriction, liver inflammation, and hepatocellular carcinoma development.

Liver fibrosis during clinical ascertainment of glycogen storage disease type III: a need for improved and systematic monitoring.

PURPOSE: In glycogen storage disease type III (GSD III), liver aminotransferases tend to normalize with age giving an impression that hepatic manifestations improve with age. However, despite dietary treatment, long-term liver complications emerge. We present a GSD III liver natural history study in children to better understand changes in hepatic parameters with age. METHODS: We reviewed clinical, biochemical, histological, and radiological data in pediatric patients with GSD III, and performed a literature review of GSD III hepatic findings. RESULTS: Twenty-six patients (median age 12.5 years, range 2-22) with GSD IIIa (n = 23) and IIIb (n = 3) were enrolled in the study. Six of seven pediatric patients showed severe fibrosis on liver biopsy (median [range] age: 1.25 [0.75-7] years). Markers of liver injury (aminotransferases), dysfunction (cholesterol, triglycerides), and glycogen storage (glucose tetrasaccharide, Glc4) were elevated at an early age, and decreased significantly thereafter (p < 0.001). Creatine phosphokinase was also elevated with no significant correlation with age (p = 0.4). CONCLUSION: Liver fibrosis can occur at an early age, and may explain the decrease in aminotransferases and Glc4 with age. Our data outlines the need for systematic follow-up and specific biochemical and radiological tools to monitor the silent course of the liver disease process.

Diagnosis and management of glycogen storage diseases type VI and IX: a clinical practice resource of the American College of Medical Genetics and Genomics (ACMG).

PURPOSE: Glycogen storage disease (GSD) types VI and IX are rare diseases of variable clinical severity affecting primarily the liver. GSD VI is caused by deficient activity of hepatic glycogen phosphorylase, an enzyme encoded by the PYGL gene. GSD IX is caused by deficient activity of phosphorylase kinase (PhK), the enzyme subunits of which are encoded by various genes: ɑ (PHKA1, PHKA2), ß (PHKB), É£ (PHKG1, PHKG2), and δ (CALM1, CALM2, CALM3). Glycogen storage disease types VI and IX have a wide spectrum of clinical manifestations and often cannot be distinguished from each other, or from other liver GSDs, on clinical presentation alone. Individuals with GSDs VI and IX can present with hepatomegaly with elevated serum transaminases, ketotic hypoglycemia, hyperlipidemia, and poor growth. This guideline for the management of GSDs VI and IX was developed as an educational resource for health-care providers to facilitate prompt and accurate diagnosis and appropriate management of patients. METHODS: A national group of experts in various aspects of GSDs VI and IX met to review the limited evidence base from the scientific literature and provided their expert opinions. Consensus was developed in each area of diagnosis, treatment, and management. Evidence bases for these rare disorders are largely based on expert opinion, particularly when targeted therapeutics that have to clear the US Food and Drug Administration (FDA) remain unavailable. RESULTS: This management guideline specifically addresses evaluation and diagnosis across multiple organ systems involved in GSDs VI and IX. Conditions to consider in a differential diagnosis stemming from presenting features and diagnostic algorithms are discussed. Aspects of diagnostic evaluation and nutritional and medical management, including care coordination, genetic counseling, and prenatal diagnosis are addressed. CONCLUSION: A guideline that will facilitate the accurate diagnosis and optimal management of patients with GSDs VI and IX was developed. This guideline will help health-care providers recognize patients with GSDs VI and IX, expedite diagnosis, and minimize adverse sequelae from delayed diagnosis and inappropriate management. It will also help identify gaps in scientific knowledge that exist today and suggest future studies.

Role of continuous glucose monitoring in the management of glycogen storage disorders.

Management of liver glycogen storage diseases (GSDs) primarily involves maintaining normoglycemia through dietary modifications and regular glucose monitoring. Self-monitoring of blood glucose is typically done 3-6 times per day, and may not sufficiently capture periods of asymptomatic hypoglycemia, particularly during sleep. Continuous glucose monitoring systems (CGMS) provide 24-h continuous glucose data and have been used effectively in diabetes mellitus to monitor metabolic control and optimize treatment. This is a relatively new approach in GSDs with only a handful of studies exploring this modality. In this study we used Dexcom CGMS to study the glycemic profile of 14 pediatric and six adult patients with GSD I, III, and IX. A total of 176 days of CGMS data were available. The CGMS was found to be a reliable tool in monitoring glucose levels and trends at all times of the day with good concordance with finger-stick glucose values. This study revealed that in addition to overnight hypoglycemia, CGMS can uncover previously undetected, subclinical, low glucose levels during daytime hours. Additionally, the CGMS detected daytime and overnight hyperglycemia, an often overlooked concern in liver GSDs. The CGMS with concurrent dietary adjustments made by a metabolic dietitian improved metabolic parameters and stabilized blood glucose levels. The CGMS was found to be a safe, effective, and reliable method for optimizing treatment in patients with GSD I, III, and IX.

Early Diagnosed and Treated Glutaric Acidemia Type 1 Female Presenting with Subependymal Nodules in Adulthood.

Glutaric acidemia type 1 (GA-1, OMIM no. 231670) is an autosomal recessive disorder caused by the deficiency of glutaryl-CoA dehydrogenase (GCDH). The subsequent accumulation of the amino acids lysine, hydroxylysine, and tryptophan and their breakdown intermediates can be neurotoxic and particularly cause injury to the basal ganglia.Roughly 1 of 100,000 infants is affected with GA-1, and a common feature at birth is macrocephaly. Stress, such as in febrile illnesses, can precipitate encephalopathic crises in children generally less than 2 years with variable recovery. Many infants develop dystonia with complex movement disorders and subtle cognitive and fine motor deficits. Common neuroradiologic findings include hypoplasia of temporal and frontal lobes, striatal lesions, white matter changes, and subdural effusions.There are three previous reports of subependymal nodules found on neuroimaging in GA-1 patients who were diagnosed as adults and untreated for GA-1. We present a unique case of an adult female who was diagnosed at age 2 months and managed prior to any metabolic decompensation. Her initial diagnosis was made based on biochemical and enzymatic analysis, and then later confirmed with genetic sequencing. She started experiencing frequent headaches at age 12 years. Neuroimaging in adulthood revealed common features seen in GA-1 in addition to the finding of subependymal nodules.This case may provide some insight into the natural progression of the disease despite early treatment. Though subependymal nodules are typically seen in tuberous sclerosis, the significance of these lesions in GA-1 is not well understood. Disease courses of more early diagnosed and treated patients with GA-1 need to be documented.

Clinical and Molecular Variability in Patients with PHKA2 Variants and Liver Phosphorylase b Kinase Deficiency.

Glycogen storage disease (GSD) type IX is a rare disease of variable clinical severity affecting primarily the liver tissue. Individuals with liver phosphorylase b kinase (PhK) deficiency (GSD IX) can present with hepatomegaly with elevated serum transaminases, ketotic hypoglycemia, hyperlipidemia, and poor growth with considerable variation in clinical severity. PhK is a cAMP-dependent protein kinase that phosphorylates the inactive form of glycogen phosphorylase, phosphorylase b, to produce the active form, phosphorylase a. PhK is a heterotetramer; the alpha 2 subunit in the liver is encoded by the X-linked PHKA2 gene. About 75% of individuals with liver PhK deficiency have mutations in the PHKA2 gene; this condition is also known as X-linked glycogenosis (XLG). Here we report the variability in clinical severity and laboratory findings in 12 male patients from 10 different families with X-linked liver PhK deficiency caused by mutations in PHKA2. We found that there is variability in the severity of clinical features, including hypoglycemia and growth. We also report additional PHKA2 variants that were identified in 24 patients suspected to have liver PhK deficiency. The basis of the clinical variation in GSDIX due to X-linked PHKA2 gene mutations is currently not well understood. Creating systematic registries, and collecting longitudinal data may help in better understanding of this rare, but common, glycogen storage disorder. SYNOPSIS: Liver phosphorylase b kinase (PhK) deficiency caused due to mutations in X-linked PHKA2 is highly variable.

Updated, web-based nutrition management guideline for PKU: An evidence and consensus based approach.

BACKGROUND: In 2014, recommendations for the nutrition management of phenylalanine hydroxylase deficiency were published as a companion to the concurrently published American College of Medical Genetics and Genomics guideline for the medical treatment of phenylketonuria (PKU). These were developed primarily from a summary of findings from the PKU scientific review conference sponsored by the National Institutes of Health and Agency for Healthcare Research & Quality along with additional systematic literature review. Since that time, the Genetic Metabolic Dietitians International and the Southeast Regional Newborn Screening and Genetics Collaborative have partnered to create a web-based technology platform for the update and development of nutrition management guidelines for inherited metabolic disorders. OBJECTIVE: The purpose of this PKU guideline is to establish harmonization in treatment and monitoring, to guide the integration of nutrition therapy in the medical management of PKU, and to improve outcomes (nutritional, cognitive, and developmental) for individuals with PKU in all life stages while reducing associated medical, educational, and social costs. METHODS: Six research questions critical to PKU nutrition management were formulated to support guideline development: Review, critical appraisal, and abstraction of peer-reviewed studies and unpublished practice literature, along with expert Delphi survey feedback, nominal group process, and external review from metabolic physicians and dietitians were utilized for development of recommendations relevant to each question. Recommendations address nutrient intake, including updated protein requirements, optimal blood phenylalanine concentrations, nutrition interventions, monitoring parameters specific to life stages, adjunct therapies, and pregnancy and lactation. Recommendations were graded using a rigorous system derived from the Academy of Nutrition and Dietetics. RESULTS AND CONCLUSION: These guidelines, updated utilizing a thorough and systematic approach to literature analysis and national consensus process, are now easily accessible to the global community via the newly developed digital platform. For additional details on specific topics, readers are encouraged to review materials on the online portal: https://GMDI.org/.