Diagnosis and follow-up of glycogen storage disease (GSD) type VI from the largest GSD center in China.

Glycogen storage disease (GSD) Type VI is a glycogenolysis disorder caused by variants of PYGL. Knowledge about this disease is limited because only approximately 50 cases have been reported. We investigated the clinical profiles, molecular diagnosis, and treatment outcomes in patients with GSD VI from 2000 to 2021. The main initial clinical features of this cohort include hepatomegaly, short stature, elevated liver transaminases, hypertriglyceridemia, fasting hypoglycemia, and hyperuricemia. After uncooked cornstarch treatment, the stature and biochemical parameters improved significantly (p < 0.05). However, hyperuricemia recurred in most patients during adolescence. Among the 56 GSD VI patients, 54 biallelic variants and two single allelic variants of PYGL were identified, of which 43 were novel. There were two hotspot variants, c.1621-258_2178-23del and c.2467C>T p.(Gln823*), mainly in patients from Southwest and South China. c.1621-258_2178-23del is a 3.6 kb deletion that results in an out-of-frame deletion r.1621_2177del and an in-frame deletion r.1621_2265del. Our data show for the first time that long-term monitoring of uric acid is recommended for older GSD VI patients. This study also broadens the variant spectrum of PYGL and indicates that there are two hot-spot variants in China.

Glycogen storage disease type VI with a novel PYGL mutation: Two case reports and literature review.

RATIONALE: Glycogen storage disease (GSD) type VI is a rare disease caused by the inherited deficiency of liver phosphorylase. PATIENT CONCERNS: The proband, a 61-month-old Chinese boy, manifested intermittent hematochezia, growth retardation, hepatomegaly, damage of liver function, mild hypoglycemia, and hyperlactatemia. The other patient was a 107-month-old Chinese girl with growth retardation, hepatomegaly, mild hypoglycemia, and hyperlactatemia. In order to further confirm the diagnosis, we conducted a liver biopsy and detected blood samples for their gene using IDT exon chip capture and high-throughput sequencing. DIAGNOSES: According to the clinical symptoms, physical examination, laboratory examinations, liver biopsy, and the genetic test finding, the 2 patients were diagnosed GSD VI. INTERVENTIONS: They were treated mainly with uncooked cornstarch. OUTCOMES: There were 2 mutations of PYGL gene in this pedigree. c.2467C>T (p. Q823X) and c.2178-2A>C occurred both in the proband and his second sister. LESSONS: As a novel mutation, c.2178-2A>C enriches the mutation spectrum of PYGL gene. The different degrees of elevated lactate is an unusual phenotype in GSD VI patients. It is not clear if this is caused by the new mutation of c. 2178-2A > C. Long-term complications remains to be observed.

Liver histology in children with glycogen storage disorders type VI and IX.

BACKGROUND: Glycogen storage diseases (GSD) type VI and IX are caused by liver phosphorylase system deficiencies and the two types are clinically indistinguishable. AIM: As the role of liver biopsy is increasingly questioned, we aim to assess its current value in clinical practice. METHODS: We retrospectively reviewed children with diagnosis of GSD VI and IX at a paediatric liver centre between 2001 and 2018. Clinical features, molecular analysis and imaging were reviewed. Liver histology was reassessed by a single histopatologist. RESULTS: Twenty-two cases were identified (9 type VI, 9 IXa, 1 IXb and 3 IXc). Features at presentation were hepatomegaly (95%), deranged AST (81%), short stature (50%) and failure to thrive (4%). Liver biopsy was performed in 19 patients. Fibrosis varied in GSD IXa with METAVIR score between F1-F3 and ISHAK score of F2-F5. METAVIR score was F2-F3 in GSD VI and F3-F4 in GSD IXc. Hepatocyte glycogenation, mild steatosis, lobular inflammatory activity and periportal copper binding protein staining were also demonstrated. CONCLUSIONS: Although GSD VI and IX are considered clinically mild, chronic histological changes of varying severity could be seen in all liver biopsies. Histopathological assessment of the liver involvement is superior to biochemical parameters, but definitive classification requires a mutational analysis.

Glycogen Storage Disease Type VI With a Novel Mutation in PYGL Gene.

BACKGROUND: Glycogen storage disease type VI (GSD-VI) presents with failure to thrive and also fibrosis in some cases, without cirrhosis. CASE CHARACTERISTICS: 2½-year-old girl presented with short stature, transaminase elevation and significant fibrosis, suggesting GSD-III. OBSERVATION: A pathogenic mutation in PYGL gene suggested GSD-VI. MESSAGE: GSD-VI should be a differential diagnosis whenever GSD-III is suspected.

Hepatic glycogen storage disorders: what have we learned in recent years?

PURPOSE OF REVIEW: Glycogen storage disorders (GSDs) are inborn errors of metabolism with abnormal storage or utilization of glycogen. The present review focuses on recent advances in hepatic GSD types I, III and VI/IX, with emphasis on clinical aspects and treatment. RECENT FINDINGS: Evidence accumulates that poor metabolic control is a risk factor for the development of long-term complications, such as liver adenomas, low bone density/osteoporosis, and kidney disease in GSD I. However, mechanisms leading to these complications remain poorly understood and are being investigated. Molecular causes underlying neutropenia and neutrophil dysfunction in GSD I have been elucidated. Case series provide new insights into the natural course and outcome of GSD types VI and IX. For GSD III, a high protein/fat diet has been reported to improve (cardio)myopathy, but the beneficial effect of this dietary concept on muscle and liver disease manifestations needs to be further established in prospective studies. SUMMARY: Although further knowledge has been gained regarding pathophysiology, disease course, treatment, and complications of hepatic GSDs, more controlled prospective studies are needed to assess effects of different dietary and medical treatment options on long-term outcome and quality of life.

[Mitochondrial dysfunction in children with hepatic forms of glycogen storage disease].

AIM: The purpose of the study was to assess mitochondrial dysfunction severity in patients with hepatic forms of glycogen storage disease (GSD). PATIENTS AND METHODS: We examined 53 children with GSD in the dynamics. Distribution of children by disease types was: 1st group--children with GSD type I, 2nd group--children with GSD type III, 3rd group--children with GSD type VI and IX; comparison group consisted of 34 healthy children. Intracellular dehydrogenases activity: succinate dehydrogenase (SDH), glycerol-3-phosphate-dehydrogenase (GPDH). nicotinamideadenin-H-dehydrogenase (NADH-D) and lactatdehydrogenase (LDH) was measured using the quantitative cytochemical method in the peripheral lymphocytes. RESULTS: It was revealed decrease of SDH- (p < 0.001) and GPDH-activities (p < 0.001), along with increase of the NADH-D activity (p < 0.05) in all patients with GSD, (SDH/ NADH-D) index was decreased (p < 0.001). LDH activity was increased in groups 1 (p < 0.05) and 3 (p < 0.01), compared with comparison group. The most pronounced intracellular enzymes activity deviations were observed in children with GSD type I, that correspond to more severe clinical form of GSD. It was found strong correlation between intracellular enzymes activity and both hepatomegaly level (R = 0.867) and metabolic acidosis severity (R = 0.987). CONCLUSION: Our investigation revealed features of mitochondrial dysfunction in children with GSD, depending on the GSD type. Activities of lymphocytes enzymes correlates with the main disease severity parameters and can be used as an additional diagnostic criteria in children with hepatic form of GSD.

Effect of clonidine on the height of a child with glycogen storage disease type VI: a 13 year follow-up study.

A 9-month-old male was found to have hepatomegaly when he was treated by his doctor for bronchitis. At the age of 2 years and 3 months, glycogen storage disease (GSD) of type VI (GSD VI) was diagnosed in this patient. Despite the recommended diet therapy, his growth was not good, changing under or along the line of -2.0 SD. At the age of 6 years, oral clonidine therapy (0.15 mg/day, 0.2 mg/m2 body surface per day) was started. Six to 10 months after the initiation of clonidine therapy, his height began to increase more than the values for -2.0 SD and once reached the value for -1.0 SD at the age of 10 years. His growth rate and bone age increased. Clonidine therapy was continued regularly for 7 years until the age of 13 years, 11 months. At that time his development was normal and his height reached 150.8 cm (-1.34 SD). However, cessation of the treatment at the patient's free will resulted in a reduction of the growth rate at age 15 years 6 months. These observations suggest the effect of clonidine therapy on height. Side effects were not noted during the clonidine therapy. Other clinical and laboratory findings of GSD VI also completely improved during treatment. In conclusion, administration of clonidine could be another treatment modality in children with GSD, not only of type VI but also I and III.

[Hepatic glycogenosis: the clinical, biochemical and enzymatic aspects in a group of pediatric patients]. / Glucogenosis hepática: aspectos clínicos, bioquímicos y enzimáticos en un grupo de pacientes pediátricos.

Nine children with clinical diagnosis of glycogenoses were studied, types were confirmed through determination of levels and structure of glycogen, stimulation with glucagon and enzymatic defect analyses. Eight patients suffered glycogenoses type III and one, type VI. The major age group un type III was 1 to 2 years old (62.5%), the type VI was diagnosed in a preschool boy. Mean clinical features were: hepatomegaly, doll-like facies and short height. Major biochemical alterations were: transaminases elevation in both types, hypertriglyceridemia, hyperglycemia, metabolic acidosis and hyperuricemia only in glycogenoses III. One III type patient presented cardiovascular alterations. All patients showed increased concentrations of erythrocyte glycogen, with normal structure in type VI and abnormal in 75% of type III. Tree fourths of type III patients had a positive response to glucagon stimulation. No one presented glucose 6 phosphatase deficiency.

[Determination of blood level of muscle enzymes in glycogenoses with liver involvement: a diagnostic criterion]. / La détermination du taux sérique des enzymes musculaires au cours des glycogénoses avec atteinte hépatique: un critère d'orientation diagnostique.

Serum muscle enzyme activity assays were routinely performed in 36 patients with glycogen storage diseases (15 types 1a and 1b, 12 type III, and 9 types VI and IX). Creatine phosphokinase serum activity was increased only in type III. Glutamate-pyruvate transaminase, aldolase and lactate dehydrogenase serum activities were increased in all the forms of glycogen storage disease studied. Muscle involvement may at least partly explain the increased serum enzyme activities in type III.

Use of platelets, mononuclear and polymorphonuclear cells in the diagnosis of glycogen storage disease type VI.

We determined glycogen concentration and phosphorylase 'a+b' and phosphorylase a activities in platelets, mononuclear and polymorphonuclear cells from control subjects and patients with phosphorylase kinase deficiency (glycogen storage disease IX) and liver phosphorylase deficiency (glycogen storage disease VI). Variations according to cellular type and to subjects' age (1-40 years) were established. Variable glycogen overloading was found in all our patients. Glycogen storage disease (GSD) VI was characterized by a diminished total phosphorylase activity with a low or normal a/(a+b) ratio of phosphorylase activity. GSD IX was characterized by a very low residual activity of phosphorylase a with an 'a+b' activity low or normal.

[Genetic heterogeneity and the diagnosis of hepatic glycogenoses]. / Hétérogénéité génétique et diagnostic des glycogénoses hépatiques.

Glycogen storage diseases constitute a highly heterogeneous group of disorders, because of the many complex enzyme systems involved in glycogen metabolism, and also because of the diversity of molecular defects connected with gene mutations. To illustrate these features, the authors studied four types of liver glycogen storage diseases, respectively caused by deficiencies of glucose-6-phosphatase, debranching enzyme, phosphorylase and phosphorylase kinase. In each case, the role and functional characteristics of the enzyme system are described, as well as the bioclinical aspects of the deficiency. The only reliable way of diagnosing glycogen storage disease is by assaying the activity of the enzyme concerned. Assay procedure must take account of various factors, especially the progress made in understanding the nature and mechanism of action of enzyme systems, the possible tissular heterogeneity of the deficiency and the functional characteristics of certain enzymes.

[Differential diagnosis of glycogenoses]. / Differentsial'naia diagnostika glikogenozov.

Different types of hepatic, muscular, and generalized forms of glycogen stogare disease, a hereditary disease caused by glycogen metabolism disorders, are analysed. The clinical and biochemical features of these diseases are described. The data on enzyme defects and methods for their detection in different types of glycogenoses as well as on the prevalence of the disease in different countries are presented.

[Hereditary storage diseases of the liver (author's transl)]. / Hereditäre Speicherkrankheiten der Leber.

Storage diseases of the liver are reviewed, classified according to the clinical symptoms. Glycogen storage diseases go along with enlargement of the liver, - the size of the spleen being normal in the beginning; presenting symptoms in many cases are metabolic disturbances as for instance hypoglycemia. Acute symptoms due to derangement of liver function occur in galactosemia and in hereditary fructose intolerance when uptake of the hexoses is not tolerated. Splenomegaly and hepatomegaly are typical in certain lipid storage diseases; these diseases may as well exhibit hematologic symptoms. Bone dysplasias are discussed finally, which use to go along with enlargement of the liver due to storage of compounds not metabolized.