Predominance of the c.648G > T G6PC gene mutation and late complications in Korean patients with glycogen storage disease type Ia

Antiadipogenic Effect of Citrus Flavonoids: Evidence from RNA Sequencing Analysis and Activation of AMPK in 3T3-L1 Adipocytes

Citrus fruits are rich in dietary flavonoids and have many health benefits, but their antiadipogenic mechanism of action and their impact on lipid metabolism remain unclear. In this study, we investigated the effect of citrus flavonoids, namely, hesperidin (HES), narirutin (NAR), nobiletin (NOB), sinensetin (SIN), and tangeretin (TAN), on preventing fat cell development by gene expression in 3T3-L1 adipocytes. Among the citrus flavonoids tested, HES and NAR significantly reduced fat storage and triglyceride levels and increased glucose uptake in 3T3-L1 adipocytes. Additionally, HES and NAR treatment increased the phosphorylation of AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC) while reducing the protein expression of 3-hydroxy-3-methylglutaryl CoA reductase (HMGCR). Furthermore, in silico docking revealed that flavonoids activate AMPK. RNA sequencing analysis demonstrated that citrus flavonoids normalized the expression of 40 genes, which were either upregulated by more than 2-fold or downregulated by less than 0.6-fold including Acadv1, Acly, Akr1d1, Awat1, Cyp27a1, Decr1, Dhrs4, Elovl3, Fasn, G6pc, Gba, Hmgcs1, Mogat2, Lrp5, Sptlc3, and Snca to levels comparable to the control group. Altogether, HES and NAR among five citrus flavonoids showed antiadipogenic effects by regulating the expression of specific lipid metabolism genes partially restored to control levels in 3T3-L1 cells.

A case of glycogen storage disease type a with gout as the first manifestation

A 24-year-old male was admitted due to recurrent redness, swelling, fever and pain in the ankle, frequently accompanied by hungry feeling. Dual energy CT scans showed multiple small gouty stones in the posterior edge of the bilateral calcaneus and in the space between the bilateral metatarsophalangeal joints. The laboratory examination results indicated hyperlipidemia, high lactate lipids, and low fasting blood glucose. Histopathology of liver biopsy showed significant glycogen accumulation. The results of gene sequencing revealed the compound heterozygous mutations of the G6PC gene c.248G>A (p.Arg83His) and c.238T>A (p.Phe80Ile) in the proband. The c.248G>A mutation was from mother and the c.238T>A mutation was from father. The diagnosis of glycogen storage disease type Ⅰa was confirmed. After giving a high starch diet and limiting monosaccharide intake, as well as receiving uric acid and blood lipids lowering therapy, the condition of the patient was gradually stabilized. After a one-year follow-up, there were no acute episodes of gout and a significant improvement in hungry feeling in the patient.

Estimation of Health Utility Scores for Glycogen Storage Disease Type Ia

BACKGROUND

Glycogen Storage Disease Type Ia (GSDIa) is a rare genetic metabolic disorder characterized by hypoglycemia, hepatomegaly, growth failure, and possible seizures/death. Patients frequently consume cornstarch to maintain blood glucose. Evidence demonstrating the impact of GSDIa on health-related quality of life (HRQoL) is lacking. This study aims to understand the burden of GSDIa by obtaining utility values for economic appraisals.

METHODS

A targeted literature review and interviews with experts (n = 4) and caregivers (n = 4) informed the development of health state vignettes describing different GSDIa severities by age and level of hypothetical treatment (i.e., gene therapy) response. Health states reflecting caregivers' experiences were also developed. A convenience sample of the UK general public completed a time trade-off (TTO) exercise. Scores conceptually varied from 0 (dead) to 1 (full health). States were also rated using a visual analog scale (VAS) and the EQ-5D-5L. Data were descriptively summarized.

RESULTS

One hundred participants completed the exercise (male: 48%; mean age: 42 years). Scores were lowest for the adolescent pre-treatment state (TTO = 0.38). Large increments in HRQoL were observed for the response (adult: TTO = 0.86; child: TTO = 0.84) and complete response (adult and child: TTO = 0.94) hypothetical treatment response states. Caregiver values were lowest for the pre-treatment state (TTO = 0.57) and highest for the complete response state (TTO = 0.95). VAS and EQ-5D-5L scores followed a similar pattern.

CONCLUSION

This study found an HRQoL burden on GSDIa patients and caregivers, with potential large improvement from a hypothetical treatment. These findings may be useful for families, clinicians, regulatory agencies, and in therapy economic evaluations.

Novel AGL variants in a patient with glycogen storage disease type IIIb and pulmonary hypertension caused by pulmonary veno-occlusive disease: A case report

Glycogen storage disease type III (GSD-III) is an autosomal recessive metabolic disorder caused by mutations in the AGL gene, and may develop various types of pulmonary hypertension (PH). Here, we report a case of 24-year-old man with GSD-IIIb with two novel null variants in AGL (c.2308 + 2T>C and c.3045_3048dupTACC). He developed multi-drug-resistant pulmonary veno-occlusive disease (PVOD) and was registered as a candidate for lung transplantation. No pathogenic variants were detected in previously known causative genes for pulmonary hypertension and the underlying mechanism of coincidence of two rare diseases was unknown. We discuss the association of the loss of glycogen-debranching enzyme with incident PVOD.

Molecular, Biochemical, and Clinical Characterization of Thirteen Patients with Glycogen Storage Disease 1a in Malaysia

Background

Glycogen storage disease type 1a (GSD1a) is a rare autosomal recessive metabolic disorder characterized by hypoglycaemia, growth retardation, lactic acidosis, hepatomegaly, hyperlipidemia, and nephromegaly. GSD1a is caused by a mutation in the G6PC gene encoding glucose-6-phosphatase (G6Pase); an enzyme that catalyses the hydrolysis of glucose-6-phosphate (G6P) to phosphate and glucose.

Objective

To elaborate on the clinical findings, biochemical data, molecular genetic analysis, and short-term prognosis of 13 GSD1a patients in Malaysia.

Methods

The information about 13 clinically classified GSD1a patients was retrospectively studied. The G6PC mutation analysis was performed by PCR-DNA sequencing.

Results

Patients were presented with hepatomegaly (92%), hypoglycaemia (38%), poor weight gain (23%), and short stature (15%). Mutation analysis revealed nine heterozygous mutations; eight previously reported mutations (c.155 A > T, c.209 G > A, c.226 A > T, c.248 G > A, c.648 G > T, c.706 T > A, c.1022 T > A, c.262delG) and a novel mutation (c.325 T > C). The most common mutation found in Malaysian patients was c.648 G > T in ten patients (77%) of mostly Malay ethnicity, followed by c.248 G > A in 4 patients of Chinese ethnicity (30%). A novel missense mutation (c.325 T > C) was predicted to be disease-causing by various in silico software.

Conclusions

The establishment of G6PC molecular genetic testing will enable the detection of presymptomatic patients, assisting in genetic counselling while avoiding the invasive methods of liver biopsy.

Prevalence and Complications of Glycogen Storage Disease in South Korea: A Nationwide Population-Based Study, 2007-2018

Glycogen storage disease (GSD) is a rare disease that can cause life-threatening problems owing to metabolic errors in storing or using glycogen. The disease course of GSD remains unknown, despite medical technology advances. We determined the prevalence and complications of GSD using data from the National Health Insurance Service database. Data were collected and analyzed for the entire South Korean population with GSD during 2007–2018. GSD was defined as a combination of disease code E74.0 and rare incurable disease insurance code V117, a unique disease code combination for GSD in South Korea. Overall, 23,055 patients had the E74 disease code; 404 had an additional V117 insurance code. Most GSD patients were aged <10 years. Many complications were identified, the most common being hepatomegaly, hyperuricemia, and elevated liver enzyme levels. The most prescribed drug was α-glucosidase, followed by allopurinol. Seventy-two percent of patients were treated in pediatrics. Twenty-five patients underwent liver transplantation, and 14 died after GSD diagnosis. In South Korea, more patients than expected had GSD diagnosis and were managed accordingly. GSD causes many complications and hospitalizations, resulting in high medical expenses. Serious complications can result in liver transplantation and, eventually, death in some cases. Although the patients' condition was identified only by the disease code, this is the first study to present the current situation of GSD patients in South Korea. Because GSD patients can have dangerous medical conditions, they should be managed consistently while minimizing various complications that may occur with optimal metabolic control.

Case Report: Glycogen Storage Disease Type Ia in a Chinese Child Treated With Growth Hormone

BACKGROUND

Glycogen storage disease type Ia is a rare metabolic disorder that leads to excessive glycogen and fat accumulation in organs, characterized by hepatomegaly, hypoglycemia, lactic acidemia, hyperlipidemia, hyperuricemia, puberty delay, and growth retardation. Here, we report on a patient with glycogen storage disease type Ia treated with growth hormone.

CASE PRESENTATION

A 10-year-old boy had growth retardation for 6 years, and was admitted to clarify the cause of his short stature. We found that his bone age was 5.5 years, significantly lower than his physical age, while his serum IGF-1 and IGFBP-3 were 23.30 and 1620.0 ng/mL, respectively, both lower than normal. His medical history revealed that he had suffered from steatohepatitis, hyperlipidemia, and hypoglycemia since he was 11 months of age. Whole exome sequencing (WES) showed compound heterozygous mutations in exons 2 and 5 of the glucose-6-phosphatase (G6PC) gene on chromosome 17: c.G248A (p.R83H) and c.G648T (p.L216L). The patient was finally diagnosed with GSD Ia. After growth hormone (GH) treatment and corn starch therapy for 14 months, his height significantly increased (by 13 cm). The serum IGF-1 level increased to the normal range but his lipid levels and liver function did not significantly increase.

CONCLUSION

We describe a young patient with a compound heterozygous G6PC variant in a Chinese family; his height increased significantly after growth hormone and corn starch interventions. This case emphasizes that WES is essential for early diagnosis, and that growth hormone treatment may increase the height of patients with GSD Ia safely.

DBS Screening for Glycogen Storage Disease Type 1a: Detection of c.648G>T Mutation in G6PC by Combination of Modified Competitive Oligonucleotide Priming-PCR and Melting Curve Analysis

Glycogen storage disease type Ia (GSDIa) is an autosomal recessive disorder caused by glucose-6-phosphatase (G6PC) deficiency. GSDIa causes not only life-threatening hypoglycemia in infancy, but also hepatocellular adenoma as a long-term complication. Hepatocellular adenoma may undergo malignant transformation to hepatocellular carcinoma. New treatment approaches are keenly anticipated for the prevention of hepatic tumors. Gene replacement therapy (GRT) is a promising approach, although early treatment in infancy is essential for its safety and efficiency. Thus, GRT requires screening systems for early disease detection. In this study, we developed a screening system for GSDIa using dried blood spots (DBS) on filter paper, which can detect the most common causative mutation in the East-Asian population, c.648G>T in the G6PC gene. Our system consisted of nested PCR analysis with modified competitive oligonucleotide priming (mCOP)-PCR in the second round and melting curve analysis of the amplified products. Here, we tested 54 DBS samples from 50 c.648G (wild type) controls and four c.648T (mutant) patients. This system, using DBS samples, specifically amplified and clearly detected wild-type and mutant alleles from controls and patients, respectively. In conclusion, our system will be applicable to newborn screening for GSDIa in the real world.

Glycogen Storage Disease Type Ia Screening Using Dried Blood Spots on Filter Paper: Application of COP-PCR for Detection of the c.648G>T G6PC Gene Mutation

Glycogen storage disease type Ia (GSDIa, OMIM #232200) is an autosomal recessive metabolic disease characterized by impaired glucose homeostasis and has a long-term complication of hepatocellular adenoma/carcinoma. GSDIa is caused by deleterious mutations in the glucose-6-phosphatase gene (G6PC). Recent studies have suggested that early treatment by gene replacement therapy may be a good solution to correct the glucose metabolism and prevent serious late complications. Early treatment of the disease needs an early disease detection system. Thus, we aimed to develop a screening system for GSDIa using dried blood spots (DBS) to detect the c.648G>T mutation in G6PC, which is a frequent mutation in the East Asian population. In this study, a total of 51 DBS samples (50 healthy controls and one patient with c.648G>T) were tested by modified competitive oligonucleotide priming PCR (mCOP-PCR). In control DBS samples, the c.648G allele was amplified at lower Cq (quantification cycle) values (<11), while the c.648T allele was amplified at higher Cq values (>14). In the patient DBS sample, the c.648T allele was amplified at a lower Cq value (<11), and the c.648G allele was amplified at a higher Cq value (>14). Based on these findings, we concluded that our mCOP-PCR system clearly differentiated the wild-type and mutant alleles, and may be applicable for screening for GSDIa with the c.648G>T mutation in G6PC.

Dried Blood Spot Screening System for Spinal Muscular Atrophy with Allele-Specific Polymerase Chain Reaction and Melting Peak Analysis

Background and Aim: Spinal muscular atrophy (SMA) is a lower motor neuron disease with autosomal recessive inheritance caused by homozygous SMN1 deletions. Although SMA has been considered as incurable, newly developed drugs improve life prognoses and motor functions of patients. To maximize the efficacy of the drugs, SMA patients should be treated before symptoms become apparent. Thus, newborn screening for SMA is strongly recommended. In this study, we aim to establish a new simple screening system based on DNA melting peak analysis. Materials and Methods: A total of 124 dried blood spot (DBS) on FTA^® ELUTE cards (51 SMN1-deleted patients with SMA, 20 carriers, and 53 controls) were punched and subjected to direct amplification of SMN1 and CFTR (reference gene). Melting peak analyses were performed to detect SMN1 deletions from DBS samples. Results: A combination of allele-specific polymerase chain reaction (PCR) and melting peak analyses clearly distinguished the DBS samples with and without SMN1. Compared with the results of fresh blood samples, our new system yielded 100% sensitivity and specificity. The advantages of our system include (1) biosafe collection, transfer, and storage for DBS samples, (2) obviating the need for DNA extraction from DBS preventing contamination, (3) preclusion of fluorescent probes leading to low PCR cost, and (4) fast and high-throughput screening for SMN1 deletions. Conclusion: We demonstrate that our system would be applicable to a real-world newborn screening program for SMA, because our new technology is efficient for use in routine clinical laboratories that do not have highly advanced PCR instruments.

The GBA p.G85E mutation in Korean patients with non-neuronopathic Gaucher disease: founder and neuroprotective effects

Background

Gaucher disease (GD) is caused by a deficiency of β-glucocerebrosidase, encoded by GBA. Haplotype analyses previously demonstrated founder effects for particular GBA mutations in Ashkenazi Jewish and French-Canadian populations. This study aimed to investigate the clinical characteristics and mutation spectrum of GBA in Korean GD patients and to identify founder effect of GBA p.G85E in non-neuronopathic GD patients.

Results

The study cohort included 62 GD patients from 58 unrelated families. Among them, 18 patients from 17 families harbored the p.G85E mutation. Haplotype analysis was performed for 9 probands and their parents for whom DNA samples were available. In 58 unrelated probands, the GBA mutation p.L483P was the most common (30/116 alleles, 26%), followed by p.G85E (16%), p.F252I (13%), and p.R296Q (9%). The median age at diagnosis of the 18 patients harboring the p.G85E mutation was 3.8 (range 1.2–57) years. No patients developed neurological symptoms during follow-up periods of 2.2–20.3 (median 13.9) years. The size of the shared haplotype containing GBA p.G85E was 732 kbp, leading to an estimated age of 3075 years.

Conclusion

The GBA p.G85E mutation, which appears to be neuroprotective despite producing distinctive visceromegaly and skeletal symptoms, exhibited a potential founder effect in Korean GD patients.

Molecular Diagnosis of Panel-Based Next-Generation Sequencing Approach and Clinical Symptoms in Patients With Glycogen Storage Disease: A Single Center Retrospective Study

Aim: The aim of this study was to investigate the clinical utility of panel-based next-generation sequencing (NGS) in the diagnostic approach of glycogen storage disease (GSD). Methods: We performed a retrospective review of the 32 cases with suspected GSDs between April 2013 and November 2019 through panel-based NGS, clinical and biochemical data and long-term complications. Results: Of the 32 clinical cases, we identified 41 different variants, including 24 missense (58.5%), one synonymous (2.4%), three nonsense (8%), one splice (2.4%), four frameshift (9.8%), one deletion (2.4%), four insertions (9.8%), two deletion-insertion (4.9%) and one duplication(2.4%), of which 13(31.7%) were previously unreported in the literature. In addition, patients with different types of GSDs showed important differences in biochemical parameters (i.e., CK, rGGT, TG, and UA). Conclusions: The panel-based NGS played an important diagnostic role in the suspicious GSDs patients, especially in the mild phenotype and ruled out detectable pathologic conditions. Besides, differences between our GSDs patients reflect biochemical heterogeneity.