RESUMO
BACKGROUND: Glycogen storage disorder (GSD) type IIIa is a rare inherited genetic disorder affecting liver and muscle tissue. Liver transplantation (LT) improves metabolic control, but muscle involvement persists. CASE: We report the case of a 31-year-old man who underwent orthotopic LT for end-stage liver disease caused by GSD type IIIa. After LT, he developed worsening clinical signs of myopathy, along with exponentially increasing levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) and creatine kinase. Liver-related elevations of AST and ALT were excluded through liver biopsy and endoscopic cholangiography; consequently, AST and ALT elevations were attributed to the underlying muscle involvement. Exacerbation of muscle disease after LT could be attributed to restoration of liver glycogen metabolism after LT, leading to increased glucose accumulation in muscle cells, where the gene defect persists. A dietary intervention with a high-protein, ketogenic diet was initiated but did not lead to significant improvement of myalgia. CONCLUSION: LT exacerbated muscle disease in a patient with GSD type IIIa. Patients should be counseled about this possible side effect of LT in GSD type IIIa.
Assuntos
Transplante de Fígado , Doenças Musculares , Humanos , Masculino , Adulto , Doenças Musculares/etiologia , Doença de Depósito de Glicogênio Tipo III/genética , Doença de Depósito de Glicogênio Tipo III/cirurgiaRESUMO
Glycogen storage disease type III (GSDIII) is a rare inborn error of metabolism affecting liver, skeletal muscle, and heart due to mutations of the AGL gene encoding for the glycogen debranching enzyme (GDE). No curative treatment exists for GSDIII. The 4.6 kb GDE cDNA represents the major technical challenge toward the development of a single recombinant adeno-associated virus-derived (rAAV-derived) vector gene therapy strategy. Using information on GDE structure and molecular modeling, we generated multiple truncated GDEs. Among them, an N-terminal-truncated mutant, ΔNter2-GDE, had a similar efficacy in vivo compared with the full-size enzyme. A rAAV vector expressing ΔNter2-GDE allowed significant glycogen reduction in heart and muscle of Agl-/- mice 3 months after i.v. injection, as well as normalization of histology features and restoration of muscle strength. Similarly, glycogen accumulation and histological features were corrected in a recently generated Agl-/- rat model. Finally, transduction with rAAV vectors encoding ΔNter2-GDE corrected glycogen accumulation in an in vitro human skeletal muscle cellular model of GSDIII. In conclusion, our results demonstrated the ability of a single rAAV vector expressing a functional mini-GDE transgene to correct the muscle and heart phenotype in multiple models of GSDIII, supporting its clinical translation to patients with GSDIII.
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Sistema da Enzima Desramificadora do Glicogênio , Doença de Depósito de Glicogênio Tipo III , Humanos , Camundongos , Ratos , Animais , Doença de Depósito de Glicogênio Tipo III/genética , Doença de Depósito de Glicogênio Tipo III/terapia , Sistema da Enzima Desramificadora do Glicogênio/genética , Músculo Esquelético/metabolismo , Glicogênio/metabolismo , TransgenesRESUMO
PURPOSE: Glycogen storage disease type III (GSD III) is a rare inherited metabolic disease characterized by excessive accumulation of glycogen in liver, skeletal muscle, and heart. Currently, there are no widely available noninvasive methods to assess tissue glycogen levels and disease load. Here, we use glycogen nuclear Overhauser effect (glycoNOE) MRI to quantify hepatic glycogen levels in a mouse model of GSD III. METHODS: Agl knockout mice (n = 13) and wild-type controls (n = 10) were scanned for liver glycogen content using glycoNOE MRI. All mice were fasted for 12 to 16 h before MRI scans. GlycoNOE signal was quantified by fitting the Z-spectrum using a four-pool Voigt lineshape model. Next, the fitted direct water saturation pool was removed and glycoNOE signal was estimated from the integral of the residual Z spectrum within -0.6 to -1.4 ppm. Glycogen concentration was also measured ex vivo using a biochemical assay. RESULTS: GlycoNOE MRI clearly distinguished Agl knockout mice from wild-type controls, showing a statistically significant difference in glycoNOE signals in the livers across genotypes. There was a linear correlation between glycoNOE signal and glycogen concentration determined by the biochemical assay. The obtained glycoNOE maps of mouse livers also showed higher glycogen levels in Agl knockout mice compared to wild-type mice. CONCLUSION: GlycoNOE MRI was used successfully as a noninvasive method to detect liver glycogen levels in mice, suggesting the potential of this method to be applied to assess glycogen storage diseases.
Assuntos
Doença de Depósito de Glicogênio Tipo III , Animais , Camundongos , Doença de Depósito de Glicogênio Tipo III/diagnóstico por imagem , Doença de Depósito de Glicogênio Tipo III/genética , Glicogênio/metabolismo , Glicogênio Hepático , Modelos Animais de Doenças , Imageamento por Ressonância Magnética , Camundongos KnockoutRESUMO
BACKGROUND: Glycogen storage disease type III (GSD III) is a rare autosomal recessive glycogenolysis disorder due to AGL gene variants, characterized by hepatomegaly, fasting hypoglycemia, hyperlipidemia, elevated hepatic transaminases, growth retardation, progressive myopathy, and cardiomyopathy. However, it is not easy to make a definite diagnosis in early stage of disease only based on the clinical phenotype and imageology due to its clinical heterogeneity. CASE PRESENTATION: We report a two-year-old girl with GSD III from a nonconsanguineous Chinese family, who presented with hepatomegaly, fasting hypoglycemia, hyperlipidemia, elevated levels of transaminases. Accordingly, Sanger sequencing, wholeexome sequencing of family trios, and qRT-PCR was performed, which revealed that the patient carried the compound heterogeneous variants, a novel frameshift mutation c.597delG (p. Q199Hfs*2) and a novel large gene fragment deletion of the entire exon 13 in AGL gene. The deletion of AGL was inherited from the proband's father and the c.597delG variant was from the mother. CONCLUSIONS: In this study, we identified two novel variants c.597delG (p. Q199Hfs*2) and deletion of the entire exon 13 in AGL in a Chinese GSD III patient. We extend the mutation spectrum of AGL. We suggest that high-throughput sequencing technology can detect and screen pathogenic variant, which is a scientific basis about genetic counseling and clinical diagnosis.
Assuntos
Doença de Depósito de Glicogênio Tipo III , Hipoglicemia , China , Doença de Depósito de Glicogênio Tipo III/diagnóstico , Doença de Depósito de Glicogênio Tipo III/genética , Hepatomegalia , Humanos , Mutação , TransaminasesRESUMO
OBJECTIVES: To reveal the different clinical presentations of liver glycogen storage disease type IX (GSD IX), which is a clinically and genetically heterogeneous type of glycogenosis. METHODS: The data from the electronic hospital records of 25 patients diagnosed with liver GSD IX was reviewed. Symptoms, clinical findings, and laboratory and molecular analysis were assessed. RESULTS: Of the patients, 10 had complaints of short stature in the initial presentation additionally other clinical findings. Elevated serum transaminases were found in 20 patients, and hepatomegaly was found in 22 patients. Interestingly, three patients were referred due to neurodevelopmental delay and hypotonia, while one was referred for only autism. One patient who presented with neurodevelopmental delay developed hepatomegaly and elevated transaminases during the disease later on. Three of the patients had low hemoglobin A1C and fructosamine values that were near the lowest reference range. Two patients had left ventricular hypertrophy. Three patients developed osteopenia during follow-up, and one patient had osteoporosis after puberty. The most common gene variant, PHKA2, was observed in 16 patients, 10 variants were novel and six variants were defined before. Six patients had variants in PHKG2, two variants were not defined before and four variants were defined before. PHKB variants were found in three patients. One patient had two novel splice site mutations in trans position. It was revealed that one novel homozygous variant and one defined homozygous variant were found in PHKB. CONCLUSIONS: This study revealed that GSD IX may present with only hypotonia and neurodevelopmental delay without liver involvement in the early infantile period. It should be emphasized that although liver GSDIX is thought of as a benign disease, it might present with multisystemic involvement and patients should be screened with echocardiography, bone mineral densitometry, and psychometric evaluation.
Assuntos
Doença de Depósito de Glicogênio Tipo III , Doença de Depósito de Glicogênio , Doença de Depósito de Glicogênio/diagnóstico , Doença de Depósito de Glicogênio/genética , Doença de Depósito de Glicogênio Tipo III/diagnóstico , Doença de Depósito de Glicogênio Tipo III/genética , Hepatomegalia , Humanos , Mutação , Fosforilase Quinase/genéticaRESUMO
OBJECTIVE: To explore the clinical features and genetic basis of two children with glycogen storage disease type III (GSD III). METHODS: The probands and their parents were subjected to genetic testing, and the pathogenity of candidate variants was analyzed by using bioinformatic tools. RESULTS: Sequencing has identified compound heterozygous variants of the AGL gene in both children, namely c.1423+1G>A and c.3701-2A>G in case 1, and c.4213_c.4214insA (p.Glu1405Glufs*17) and c.3589-3C>G in case 2. Both children were diagnosed with GSD III. Literature review suggested that the main type variant among Chinese patients with GSD III involve splice sites of the AGL gene, with c.1735+1G>T being the most common. Based on the American College of Medical Genetics and Genomics standards and guidelines,c.1423+1G>A, c.3701-2A>G and c.4213_c.4214insA variants of AGL gene were predicted to be of pathogenic (PVS1+PM2+PM3, PVS1+PM2+PM3, PVS1+PM2+PP5), and c.3589-3C>G variant was predicted to be of uncertain significance (PM2+PM3+PP3). CONCLUSION: The compound heterozygous variants of the AGL gene probably underlay the GSD III in both children. Above findings have enriched the spectrum of genetic variants underlying this disease.
Assuntos
Doença de Depósito de Glicogênio Tipo III , Criança , Testes Genéticos , Genômica , Doença de Depósito de Glicogênio Tipo III/genética , Humanos , MutaçãoRESUMO
Objectives To investigate the clinical and genetic characteristics of children with glycogen storage disease type IIIa (GSD IIIa) and to explore the muscle involvement and manifestations of GSD IIIa patients. Methods The clinical data of 11 patients with GSD IIIa diagnosed by genetic testing from 2003 to 2019 were retrospectively analyzed. Results Twenty variants of AGL gene were detected in 11 patients, eight of which were novel variants. Before treatment, the height was significantly backward. All patients had hepatomegaly. Abnormal biochemical indicators were mainly manifested as significantly increased serum liver and muscle enzymes, accompanied by hypertriglyceridemia, hypoglycemia, hyperlactacidemia, slightly elevated pyruvic acid, and metabolic acidosis. After treatment, the height and liver size of the patients were significantly improved. At the same time, alanine aminotransferase (ALT), aspartate aminotransferase (AST), triglyceride (TG), lactic acid and pyruvic acid in children were significantly decreased, while creatine kinase (CK) was significantly increased. During follow-up monitoring, six patients developed ventricular hypertrophy. Lactate dehydrogenase (LDH) (691.67 ± 545.27 vs. 362.20 ± 98.66), lactic acid (3.18 ± 3.05 vs. 1.10 ± 0.40), and pyruvic acid (64.30 ± 39.69 vs. 32.06 ± 4.61) were significantly increased in patients with ventricular hypertrophy compared with those without ventricular hypertrophy. Conclusions In clinical cases of upper respiratory tract infection or gastrointestinal symptoms accompanied by hypoglycemia, dyslipidemia, metabolites disorders, elevated serum liver, and muscle enzymes, the possibility of GSD IIIa should be vigilant. During treatment monitoring, if lactic acid, pyruvic acid, LDH, and CK rise, it indicates that the disease is not well controlled and there is the possibility of cardiac hypertrophy.
Assuntos
Doença de Depósito de Glicogênio Tipo III/genética , Doença de Depósito de Glicogênio Tipo III/terapia , Adolescente , Criança , Pré-Escolar , Análise Mutacional de DNA , Feminino , Seguimentos , Testes Genéticos , Doença de Depósito de Glicogênio Tipo III/diagnóstico , Hepatomegalia/diagnóstico , Hepatomegalia/genética , Humanos , Lactente , Masculino , Monitorização Fisiológica , Estudos RetrospectivosAssuntos
Morte Súbita Cardíaca , Eletrocardiografia Ambulatorial/métodos , Doença de Depósito de Glicogênio Tipo III/complicações , Parada Cardíaca Extra-Hospitalar/diagnóstico , Cardiomiopatia Hipertrófica/diagnóstico por imagem , Criança , Ecocardiografia , Evolução Fatal , Feminino , Doença de Depósito de Glicogênio Tipo III/genética , Humanos , Fatores de TempoRESUMO
BACKGROUND: Glycogen storage diseases (GSD) are disorders of autosomal recessive carbohydrate metabolism, characterized by glycogen accumulation. The liver and muscle tissue are commonly affected but patients may present with different clinical manifestations. The presence of glycogen can be demonstrated in biopsies and definitive diagnosis can be made by enzymatic or molecular analysis. The aim of this study was to determine specific gene mutations in our cases with GSD. METHODS: Thirty-eight patients with clinical and laboratory diagnoses of GSD were studied. Thirty-two patients had undergone genetic analysis. In our study, a next-generation sequencing panel was used. RESULTS: Five novel variants of uncertain significance (VUS), which were likely to be pathogenic, were detected in seven patients. Two new pathogenic variations of c.927delT (p.Phe309LeufsTer4) homozygous and c.44C>G (p.Ser15Ter) homozygous in the G6PC gene were detected in two GSD type Ia patients. In our two non-sibling GSD type III patients, c.1439T>G (p.Leu480Arg) homozygous novel-VUS was detected in the AGL gene. In our GSD type IV patient, c.1054G>C (p.Asp352His) homozygous novel-VUS was detected in the GBE1 gene. In GSD type VI, two sibling patients had a c.1454A>G (p.Asn485Ser) homozygous novel-VUS change in the PYGL gene. CONCLUSIONS: We determined the gene mutations specific to cohorts in our cases with GSD. The novel pathogenic, likely pathogenic, and VUS changes identified will contribute to the relationship between the patients' clinical and laboratory findings.
Assuntos
Doença de Depósito de Glicogênio/genética , Mutação , Enzima Ramificadora de 1,4-alfa-Glucana/genética , Metabolismo dos Carboidratos/genética , Criança , Análise Mutacional de DNA , Feminino , Sistema da Enzima Desramificadora do Glicogênio/genética , Glicogênio Fosforilase/genética , Doença de Depósito de Glicogênio/patologia , Doença de Depósito de Glicogênio Tipo I/genética , Doença de Depósito de Glicogênio Tipo III/genética , Homozigoto , Humanos , Fígado/metabolismo , Fígado/patologia , Masculino , TurquiaRESUMO
Glycogen storage disease type III (GSD III) is a rare autosomal recessive inborn error of glycogen degradation pathway due to deficiency or reduced activity of glycogen debranching enzyme (GDE) that results in accumulation of abnormal glycogen in the liver, muscle, and heart. The cardinal hallmarks are hepatomegaly, fasting hypoglycemia, seizures, growth retardation, progressive skeletal myopathy, and cardiomyopathy in few. To date, 258 mutations in amyloglucosidase (AGL) gene have been identified worldwide. However, the mutation spectrum in the Asian Indian region is yet to be well characterized. We investigated 24 patients of Asian origin from 21 unrelated families with a provisional diagnosis of GSD III based on clinical and biochemical criteria. Molecular diagnosis was assessed by bidirectional sequencing and the impact of novel missense variants on the tertiary (three-dimensional) structure of GDE was evaluated by molecular modeling approach. Eighteen different pathogenic variants were identified, out of which 78% were novel. Novel variants included five nonsense, three small duplications and two small deletions, a splice site variant, and three missense variants. Variations in Exons 4, 14, 19, 24, 27, and 33 accounted for 61% of the total pathogenic variants identified and Allele p.Gly798Alafs*3 showed a high allele frequency of 11%. Molecular modeling study of novel pathogenic missense variants indicated the probable underlying molecular mechanism of adverse impact of variations on the structure and catalytic function of human GDE. Our study is the first large study on GSD III from the Asian subcontinent, which further expands the mutation spectrum of AGL.
Assuntos
Predisposição Genética para Doença , Glucana 1,4-alfa-Glucosidase/genética , Doença de Depósito de Glicogênio Tipo III/genética , Fígado/enzimologia , Alelos , Povo Asiático/genética , Criança , Pré-Escolar , Éxons/genética , Feminino , Frequência do Gene/genética , Glucana 1,4-alfa-Glucosidase/metabolismo , Doença de Depósito de Glicogênio Tipo III/epidemiologia , Doença de Depósito de Glicogênio Tipo III/patologia , Humanos , Fígado/metabolismo , Fígado/patologia , Masculino , Mutação/genéticaRESUMO
BACKGROUND: Uniparental disomy (UPD) leading to autosomal recessive (AR) diseases is rare. We found an unusual homozygous state in two nonconsanguineous families, and only one parent in each family was a heterozygote. METHODS: Two patients with homozygosity for pathogenic variants were revealed by whole-exome sequencing (WES), further Sanger sequencing found that only one of the parents was a heterozygote. Initial genotype and copy number variations analysis from WES data of probands involving whole chromosomes 1 and 9 containing these two pathogenic variants were performed, genome-wide single-nucleotide polymorphism (SNP) array analysis was used to confirm these results. RESULTS: Whole-exome sequencing identified a homozygous c.3423_3424delTG mutation in AGL in patient 1 and a homozygous c.241-1G>C mutation in SURF1 in patient 2. Further parental testing found that only the two patients' healthy fathers were heterozygous. WES-based copy number and genotype analysis found a copy-neutral loss of heterozygosity (LOH) of whole chromosome 1 in patient 1 and of whole chromosomes 9 and 10 in patient 2. Further genome-wide SNP array and family haplotype analyses confirmed whole paternal uniparental isodisomy (UPiD) 1 in patient 1 and paternal UPiD 9 and maternal UPiD 10 in patient 2. Therefore, UPiD caused AR monogenic glycogen storage disease type-III (GSDIII) in patient 1 and Leigh syndrome in patient 2 through non-Mendelian inheritance of two mutant copies of a gene from each patient's father. CONCLUSION: Our report highlights that a single NGS-based analysis could allow us to find homozygous sequence variants and copy-neutral LOH in such cases. Our report also describes the first case of GSDIII caused by UPiD 1 and Leigh syndrome caused by UPiD 9.
Assuntos
Doença de Depósito de Glicogênio Tipo III/diagnóstico , Doença de Leigh/diagnóstico , Perda de Heterozigosidade , Dissomia Uniparental/genética , Deleção de Genes , Frequência do Gene , Sistema da Enzima Desramificadora do Glicogênio/genética , Doença de Depósito de Glicogênio Tipo III/genética , Homozigoto , Humanos , Lactente , Doença de Leigh/genética , Masculino , Proteínas de Membrana/genética , Proteínas Mitocondriais/genética , Linhagem , Polimorfismo de Nucleotídeo Único , Sequenciamento do ExomaRESUMO
Glycogen storage diseases (GSDs) type I (GSDI) and type III (GSDIII), the most frequent hepatic GSDs, are due to defects in glycogen metabolism, mainly in the liver. In addition to hypoglycemia and liver pathology, renal, myeloid, or muscle complications affect GSDI and GSDIII patients. Currently, patient management is based on dietary treatment preventing severe hypoglycemia and increasing the lifespan of patients. However, most of the patients develop long-term pathologies. In the past years, gene therapy for GSDI has generated proof of concept for hepatic GSDs. This resulted in a recent clinical trial of adeno-associated virus (AAV)-based gene replacement for GSDIa. However, the current limitations of AAV-mediated gene transfer still represent a challenge for successful gene therapy in GSDI and GSDIII. Indeed, transgene loss over time was observed in GSDI liver, possibly due to the degeneration of hepatocytes underlying the physiopathology of both GSDI and GSDIII and leading to hepatic tumor development. Moreover, multitissue targeting requires high vector doses to target nonpermissive tissues such as muscle and kidney. Interestingly, recent pharmacological interventions or dietary regimen aiming at the amelioration of the hepatocyte abnormalities before the administration of gene therapy demonstrated improved efficacy in GSDs. In this review, we describe the advances in gene therapy and the limitations to be overcome to achieve efficient and safe gene transfer in GSDs.
Assuntos
Dependovirus/genética , Terapia Genética/métodos , Glucose-6-Fosfatase/genética , Doença de Depósito de Glicogênio Tipo III/terapia , Doença de Depósito de Glicogênio Tipo I/terapia , Hipoglicemia/terapia , Animais , Ensaios Clínicos como Assunto , Dependovirus/metabolismo , Modelos Animais de Doenças , Técnicas de Transferência de Genes , Vetores Genéticos/química , Vetores Genéticos/metabolismo , Glucose-6-Fosfatase/metabolismo , Glicogênio/biossíntese , Doença de Depósito de Glicogênio Tipo I/enzimologia , Doença de Depósito de Glicogênio Tipo I/genética , Doença de Depósito de Glicogênio Tipo I/patologia , Doença de Depósito de Glicogênio Tipo III/enzimologia , Doença de Depósito de Glicogênio Tipo III/genética , Doença de Depósito de Glicogênio Tipo III/patologia , Hepatócitos/enzimologia , Hepatócitos/patologia , Humanos , Hipoglicemia/enzimologia , Hipoglicemia/genética , Hipoglicemia/patologia , Fígado/enzimologia , Fígado/patologia , TransgenesRESUMO
BACKGROUND: Glycogen storage disease type III is an autosomal recessive disorder that is caused by deficiencies of the glycogen debranching enzyme. Mutations within the AGL gene have been found to be heterogeneous, with some common mutations being reported in certain populations. The mutation spectrum of AGL gene in the multi-ethnic Malaysian population is still unknown. OBJECTIVE: The present study seeks to determine the mutation spectrum of the AGL gene in Malaysian population. METHODS: A total of eleven patients (eight Malay, two Chinese and one Bajau) were investigated. Genomic DNA was extracted and subsequently the AGL gene was amplified using specific primers and sequenced. Mutations found were screened in 150 healthy control samples either by restriction enzyme digestion assay or TaqMan® SNP Genotyping assay. RESULTS: We identified six unreported mutations (c.1423+1G>T, c.2914_2915delAA, c.3814_3815delAG, c.4333T>G, c.4490G>A, c.4531_4534delTGTC) along with three previously reported mutations (c.99C>T, c.1783C>T, c.2681+1G>A). One of the six unreported mutation causes abnormal splicing and results in retention of intron 12 of the mature transcript, while another is a termination read-through. One of the reported mutation c.2681+1G>A was recurrently found in the Malay patients (n = 7 alleles; 31.8%). CONCLUSION: The mutation spectrum of the AGL gene in Malaysian patients has shown considerable heterogeneity, and all unreported mutations were absent in all 150 healthy control samples tested.
Assuntos
Sistema da Enzima Desramificadora do Glicogênio/genética , Doença de Depósito de Glicogênio Tipo III/genética , Mutação , Criança , Pré-Escolar , Feminino , Sistema da Enzima Desramificadora do Glicogênio/metabolismo , Doença de Depósito de Glicogênio Tipo III/patologia , Humanos , Lactente , Íntrons , Masculino , Splicing de RNARESUMO
BACKGROUND: Glycogen storage disease type III (GSDIII) is caused by mutations of AGL gene with debranching enzyme deficiency. Patients with GSDIII manifest fasting hypoglycemia, hepatomegaly, hepatopathy, myopathy, and cardiomyopathy. We report on an 18-year-old boy with a profound growth retardation (<3 SD) besides typical clinical features of GSDIII, whereby endocrinological studies were negative. METHODS AND RESULTS: Molecular analysis of AGL gene revealed the homozygous reported variant c.3903_3904insA. Since discordant results from segregation studies showed the carrier status in one parent only, SNP array and short tandem repeats analyses were performed, revealing a paternal disomy of chromosome 1 (UPD1). CONCLUSION: This study describes the first case of GSDIII resulting from UPD1. UPD can play an important role even in case of imprinted genes. DIRAS3 is a maternally imprinted tumor suppressor gene, located on chromosome 1p31, and implicated in growth and oncogenesis. It can be speculated that DIRAS3 overexpression might have a role in the severe short stature of our patient. The study emphasizes the importance of parental segregation analysis especially in patients with recessive conditions to look for specific genetic causes of disease and to estimate properly the risk of family recurrence.
Assuntos
Cromossomos Humanos Par 1/genética , Nanismo/genética , Doença de Depósito de Glicogênio Tipo III/genética , Fenótipo , Dissomia Uniparental/genética , Adolescente , Nanismo/patologia , Doença de Depósito de Glicogênio Tipo III/patologia , Humanos , Masculino , Dissomia Uniparental/patologiaRESUMO
OBJECTIVES: Glycogen storage disease type 3 (GSD-III) is a rare inherited metabolic disorder caused by glycogen debranching enzyme deficiency. Various pathogenic mutations of the AGL gene lead to abnormal accumulation of glycogen in liver, skeletal, and cardiac muscles. Here, we report distinct clinical and genetic data of Iranian patients with GSD-III. METHODS: Clinical and laboratory data of 5 patients with GSD-III were recorded. Genetic investigation was performed to identify the causative mutations. RESULTS: Three patients had typical liver involvement in childhood and one was diagnosed 2 years after liver transplantation for cirrhosis of unknown etiology. Four patients had vacuolar myopathy with glycogen excess in muscle biopsy. All patients had novel homozygous mutations of the AGL gene namely c.378T>A, c.3295T>C, c.3777G>A, c.2002-2A>G, and c.1183C>T. CONCLUSIONS: This is the first comprehensive report of patients with GSD-III in Iran with 2 uncommon clinical presentations and 5 novel mutations in the AGL gene.
Assuntos
Doença de Depósito de Glicogênio Tipo III , Glicogênio/genética , Mutação/genética , Adolescente , Adulto , Feminino , Glicogênio/metabolismo , Sistema da Enzima Desramificadora do Glicogênio/genética , Doença de Depósito de Glicogênio Tipo III/genética , Doença de Depósito de Glicogênio Tipo III/fisiopatologia , Doença de Depósito de Glicogênio Tipo III/cirurgia , Doença de Depósito de Glicogênio Tipo III/terapia , Humanos , Irã (Geográfico)/epidemiologia , Transplante de Fígado/métodos , Masculino , Pessoa de Meia-Idade , Músculo Esquelético/fisiopatologia , Adulto JovemRESUMO
Glycogen storage diseases (GSDs) of the liver are devastating disorders presenting with fasting hypoglycemia as well as hepatic glycogen and lipid accumulation, which could lead to long-term liver damage. Diet control is frequently utilized to manage the potentially dangerous hypoglycemia, but there is currently no effective pharmacological treatment for preventing hepatomegaly and concurrent liver metabolic abnormalities, which could lead to fibrosis, cirrhosis, and hepatocellular adenoma or carcinoma. In this study, we demonstrate that inhibition of glycogen synthesis using an RNAi approach to silence hepatic Gys2 expression effectively prevents glycogen synthesis, glycogen accumulation, hepatomegaly, fibrosis, and nodule development in a mouse model of GSD III. Mechanistically, reduction of accumulated abnormally structured glycogen prevents proliferation of hepatocytes and activation of myofibroblasts as well as infiltration of mononuclear cells. Additionally, we show that silencing Gys2 expression reduces hepatic steatosis in a mouse model of GSD type Ia, where we hypothesize that the reduction of glycogen also reduces the production of excess glucose-6-phosphate and its subsequent diversion to lipid synthesis. Our results support therapeutic silencing of GYS2 expression to prevent glycogen and lipid accumulation, which mediate initial signals that subsequently trigger cascades of long-term liver injury in GSDs.
Assuntos
Doença de Depósito de Glicogênio Tipo III/genética , Glicogênio Sintase/genética , Glicogênio/genética , Cirrose Hepática/genética , Cirrose Hepática/patologia , Fígado/patologia , Interferência de RNA/fisiologia , Animais , Modelos Animais de Doenças , Feminino , Fibroblastos/patologia , Glucose-6-Fosfato/genética , Doença de Depósito de Glicogênio Tipo III/patologia , Hepatócitos/patologia , Hepatomegalia/genética , Masculino , Camundongos , Camundongos Endogâmicos C57BLRESUMO
INTRODUCTION: Type III glycogen storage disease (GSD III) is an autosomal recessive disorder in which a mutation in the AGL gene causes deficiency of the glycogen debranching enzyme. The disease is characterized by fasting hypoglycemia, hepatomegaly and progressive myopathy. Molecular analyses of AGL have indicated heterogeneity depending on ethnic groups. The full spectrum of AGL mutations in Colombia remains unclear. OBJECTIVE: To describe the clinical and molecular characteristics of ten Colombian patients diagnosed with GSD III. MATERIALS AND METHODS: We recruited ten Colombian children with a clinical and biochemical diagnosis of GSD III to undergo genetic testing. The full coding exons and the relevant exon-intron boundaries of the AGL underwent Sanger sequencing to identify mutation. RESULTS: All patients had the classic phenotype of the GSD III. Genetic analysis revealed a mutation p.Arg910X in two patients. One patient had the mutation p.Glu1072AspfsX36, and one case showed a compound heterozygosity with p.Arg910X and p.Glu1072AspfsX36 mutations. We also detected the deletion of AGL gene 3, 4, 5, and 6 exons in three patients. The in silico studies predicted that these defects are pathogenic. No mutations were detected in the amplified regions in three patients. CONCLUSION: We found mutations and deletions that explain the clinical phenotype of GSD III patients. This is the first report with a description of the clinical phenotype and the spectrum of AGL mutations in Colombian patients. This is important to provide appropriate prognosis and genetic counseling to the patient and their relatives.
Assuntos
Doença de Depósito de Glicogênio Tipo III/diagnóstico , Doença de Depósito de Glicogênio Tipo III/genética , Criança , Pré-Escolar , Colômbia , Feminino , Humanos , Lactente , Masculino , Mutação , Fenótipo , Deleção de SequênciaRESUMO
Resumen Introducción. La enfermedad por almacenamiento de glucógeno de tipo III es una alteración autosómica recesiva, en la cual las mutaciones del gen AGL causan una deficiencia en la enzima desramificadora de glucógeno. Se caracteriza por hipoglucemia, hepatomegalia y miopatías progresivas. El análisis molecular del gen AGL ha evidenciado mutaciones que difieren según la población estudiada. En la actualidad, no existen reportes que describan mutaciones en el AGL de pacientes colombianos con esta condición. Objetivo. Describir las características clínicas y moleculares de diez pacientes colombianos con enfermedad por almacenamiento del glucógeno de tipo III. Materiales y métodos. Se analizaron diez pacientes pediátricos colombianos con la enfermedad y se hizo su estudio genético mediante la secuenciación de las regiones que codifican y las intrónicas circundantes del gen AGL con el método de Sanger. Resultados. Todos los pacientes tenían el fenotipo clásico de la enfermedad. El estudio genético reveló la mutación p.Arg910X en dos pacientes. Uno presentó la mutación p.Glu1072AspfsX36 y otro resultó heterocigoto compuesto con las mutaciones p.Arg910X y p.Glu1072AspfsX36. Asimismo, en tres pacientes se detectó la deleción de los exones 4, 5 y 6 del gen AGL. Los estudios de simulación computacional predijeron que estos defectos eran patogénicos. En tres pacientes no se encontraron mutaciones en las regiones amplificadas. Conclusión. Se encontraron mutaciones y deleciones que explican el fenotipo clínico de los pacientes. Este es el primer reporte en el que se describe el fenotipo clínico y el espectro de mutaciones en el gen AGL de pacientes colombianos, lo cual es importante para ofrecer un apropiado pronóstico, y asesoría genética al paciente y a su familia.
Abstract Introduction: Type III glycogen storage disease (GSD III) is an autosomal recessive disorder in which a mutation in the AGL gene causes deficiency of the glycogen debranching enzyme. The disease is characterized by fasting hypoglycemia, hepatomegaly and progressive myopathy. Molecular analyses of AGL have indicated heterogeneity depending on ethnic groups. The full spectrum of AGL mutations in Colombia remains unclear. Objective: To describe the clinical and molecular characteristics of ten Colombian patients diagnosed with GSD III. Materials and methods: We recruited ten Colombian children with a clinical and biochemical diagnosis of GSD III to undergo genetic testing. The full coding exons and the relevant exon-intron boundaries of the AGL underwent Sanger sequencing to identify mutation. Results: All patients had the classic phenotype of the GSD III. Genetic analysis revealed a mutation p.Arg910X in two patients. One patient had the mutation p.Glu1072AspfsX36, and one case showed a compound heterozygosity with p.Arg910X and p.Glu1072AspfsX36 mutations. We also detected the deletion of AGL gene 3, 4, 5, and 6 exons in three patients. The in silico studies predicted that these defects are pathogenic. No mutations were detected in the amplified regions in three patients. Conclusion: We found mutations and deletions that explain the clinical phenotype of GSDIII patients. This is the first report with a description of the clinical phenotype and the spectrum of AGLmutations in Colombian patients. This is importantto provide appropriate prognosis and genetic counseling to the patient and their relatives.
Assuntos
Criança , Pré-Escolar , Feminino , Humanos , Lactente , Masculino , Doença de Depósito de Glicogênio Tipo III/diagnóstico , Doença de Depósito de Glicogênio Tipo III/genética , Fenótipo , Deleção de Sequência , Colômbia , MutaçãoRESUMO
BACKGROUND: Glycogen Storage Disease Type III (GSD III) is a rare autosomal recessive metabolic disorder caused by AGL gene mutation. There is significant heterogeneity between the clinical manifestations and the gene mutation of AGL among different ethnic groups. However, GSD III is rarely reported in Chinese population. CASE PRESENTATION: In this study, we aimed to study the genetic and clinical characteristics of four patients with GSD IIIa from China, especially the neurological manifestations. Meanwhile, we conducted a literature review of GSD IIIa cases reported in Chinese population to investigate the relationship between genotype and phenotype. CONCLUSIONS: Three different AGL gene mutations were identified in our patients: c.206dupA, c.1735 + 1G > T and c.2590 C>T. Moreover, progressive myopathy accompanied by elevated creatine kinase level was the main manifestation of our patients in adolescents. Our results showed that AGL c.206dupA was a novel mutation and caused severe clinical manifestations. AGL c.1735 + 1G > T might be a recurrent mutation in the Chinese population. Genetic analysis of AGL gene mutation combined with muscle magnetic resonance imaging (MRI) might provide greater benefit to the patient in diagnosing GSD IIIa, rather than an invasive diagnostic procedure of biopsy.
Assuntos
Creatina Quinase/metabolismo , Sistema da Enzima Desramificadora do Glicogênio/genética , Doença de Depósito de Glicogênio Tipo III/genética , Doenças Musculares/genética , Mutação , Pré-Escolar , China , Feminino , Testes Genéticos , Doença de Depósito de Glicogênio Tipo III/complicações , Doença de Depósito de Glicogênio Tipo III/metabolismo , Humanos , Lactente , Masculino , Doenças Musculares/etiologia , Doenças Musculares/metabolismo , Regulação para CimaRESUMO
Glycogen storage disease type III (GSDIII) is an autosomal recessive disorder caused by a deficiency of glycogen-debranching enzyme (GDE), which results in profound liver metabolism impairment and muscle weakness. To date, no cure is available for GSDIII and current treatments are mostly based on diet. Here we describe the development of a mouse model of GSDIII, which faithfully recapitulates the main features of the human condition. We used this model to develop and test novel therapies based on adeno-associated virus (AAV) vector-mediated gene transfer. First, we showed that overexpression of the lysosomal enzyme alpha-acid glucosidase (GAA) with an AAV vector led to a decrease in liver glycogen content but failed to reverse the disease phenotype. Using dual overlapping AAV vectors expressing the GDE transgene in muscle, we showed functional rescue with no impact on glucose metabolism. Liver expression of GDE, conversely, had a direct impact on blood glucose levels. These results provide proof of concept of correction of GSDIII with AAV vectors, and they indicate that restoration of the enzyme deficiency in muscle and liver is necessary to address both the metabolic and neuromuscular manifestations of the disease.