Objective: Glycogen storage disease type IX (GSD-IX) is a rare primary glucose metabolism abnormality caused by phosphorylase kinase deficiency and a series of pathogenic gene mutations. The clinical characteristics, gene analysis, and functional verification of a mutation in a child with hepatomegaly are summarized here to clarify the pathogenic cause of the disease. Methods: The clinical data of a child with GSD-IX was collected. Peripheral blood from the child and his parents was collected for genomic DNA extraction. The patient's gene diagnosis was performed by second-generation sequencing. The suspected mutations were verified by Sanger sequencing and bioinformatics analysis. The suspected splicing mutations were verified in vivo by RT-PCR and first-generation sequencing. Results: Hepatomegaly, transaminitis, and hypertriglyceridemia were present in children. Liver biopsy pathological examination results indicated glycogen storage disease. Gene sequencing revealed that the child had a c.285 + 2_285 + 5delTAGG hemizygous mutation in the PHKA2 gene. Sanger sequencing verification showed that the mother of the child was heterozygous and the father of the child was of the wild type. Software such as HSF3.1 and ESEfinder predicted that the gene mutation affected splicing. RT-PCR of peripheral blood from children and his mother confirmed that the mutation had caused the skipping of exon 3 during the constitutive splicing of the PHKA2 gene. Conclusion: The hemizygous mutation in the PHKA2 gene (c.285 + 2_285 + 5delTAGG) is the pathogenic cause of the patient's disease. The detection of the novel mutation site enriches the mutation spectrum of the PHKA2 gene and serves as a basis for the family's genetic counseling.
Child ; Humans ; Exons ; Glycogen Storage Disease/genetics* ; Hepatomegaly/genetics* ; Mutation ; Phosphorylase Kinase/genetics* ; Male ; Female

OBJECTIVEType III glycogen storage disease (GSD-III, McKusick 232400), is a rare autosomal recessive disorder, also known as Cori's or Forbe's disease. The affected enzyme is amylo-1,6-glucosidase, 4-alpha-glucanotransferase (glycogen debrancher enzyme, GDE or amylogluco-sidase, AGL), which is responsible for the debranching of the glycogen molecule during catabolism. The AGL gene is located on chromosome 1p21 and contains 35 exons translated in a monomeric protein product. The clinical manifestations of GSD-III are represented by hepatomegaly, recurrent hypoglycemia, seizures, growth failure, dysmorphism, hyperlipidemia, raised transaminases and creatine kinase concentrations and, in a number of subjects, myopathy and cardiomyopathy. The hepatocellular adenoma, hepatocellular carcinoma, diabetes mellitus and liver fibrosis remain rare events. The diagnosis of debrancher deficiency was established by laboratory tests, electromyography (EMG), and muscle and liver biopsy.

METHODSWe studied six GSD-III families after patients or parental consent and the clinical characteristics were documented. Analysis of 33 exons and part exon-intron boundaries of the AGL gene in patients and their parents were carried out by PCR and direct DNA sequencing.

RESULTSThe clinical features included hepatomegaly, splenomegaly, recurrent hypoglycemia, hyperlipidemia, growth failure, raised transaminases and acidosis. Administration of epinephrine 2 hours after a carbohydrate meal could provoke normal rise of blood glucose in the affected individuals, but could not evoke any response after overnight fasting. Administration of raw-corn-starch could maintain normoglycemia and improve the disease condition. Mutation analysis for patient 1 was normal. Patient 2 had a compound heterozygote: a C-to-T transition at nucleotide 1294 (come from father, 1294C > T, L 298 L) in exon 8 and a G-to-T transition at nucleotide 4747 (from mother, 4747G > T, E1450X) in exon 34. Patient 3 had a compound heterozygote: a C-to-T transition at nucleotide 1294 (from father, 1294C > T, L 298 L) in exon 8 and a G-to-A transition at nucleotide -10 (from mother, -10G > A) in exon 3. Patient 4 was a homozygote: an insertion of a nucleotide CT into position +65 in exon 35 (4664 ins CT). Patient 5 had a compound heterozygote: a 8 bp deletion at nucleotide 2341 (from father, 2341delGCCATAGA, frameshift mutation) in exon 16 and a G-to-A transition at nucleotide 1559 (from mother, 1559G > A, R 387 Q) in exon 10. Patient 6 had a compound heterozygote: a T-to-G transition at nucleotide 1686 (from mother, 1686T > G, Y429 X) in exon 12 and a G-to-A transition at nucleotide 3742 (from father, 3742G > A, G 1115 R) in exon 26.

CONCLUSIONGSD-III patients have variable phenotypic characteristics. Administration of raw-corn-starch can effectively improve the disease outcome. We identified 8 new mutations on AGL gene through nucleotide sequence analysis.

Child ; Child, Preschool ; Female ; Glycogen Debranching Enzyme System ; genetics ; Glycogen Storage Disease Type III ; genetics ; therapy ; Humans ; Male ; Mutation

The clinical data of 2 infants with infantile glycogen storage disease type II (GSD II) from one pedigree were collected. The method of dried blood spots (DBS) was applied to collect peripheral blood samples, and the activity of acid alpha-D-glucosidase (GAA) in leukocytes was measured. The coding region of GAA gene in this pedigree was amplified by polymerase chain reaction and then direct sequencing was used to analyze mutations in GAA gene. The two infants were twins, who were admitted to the hospital due to feeding difficulties, generalized muscle weakness and hypotonia, cardiomegaly, and cardiac insufficiency when they were 10 months old. The GAA activity in leukocytes in the two infants was significantly lower than in normal controls. Gene sequencing revealed 2 compound heterozygous mutations in the two infants, i.e., G1942A and G2214A, respectively. G1942A had been proved pathogenic, and the latter one, G2214A, was a nonsense mutation, resulting in the change of tryptophan, the 738th amino acid of GAA, into a stop codon. The two infants were diagnosed with GSD II by gene detection and no enzyme replacement therapy could be provided to them. Follow-up visits showed that the two infants died at home at the age of 15 months and 17 months, respectively. GSD II is caused by deficiency of GAA activity resulting from mutation of GAA gene. The detection of GAA activity in peripheral blood by DBS and GAA gene detection are effective and feasible methods for diagnosis of GSD II.
Female ; Glycogen Storage Disease Type II ; genetics ; Humans ; Infant ; Mutation ; Pedigree ; alpha-Glucosidases ; genetics

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.
Male ; Humans ; Young Adult ; Adult ; Glycogen Storage Disease Type I/genetics* ; Gout/genetics* ; Mutation ; Lipids

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.
Child ; Genetic Testing ; Genomics ; Glycogen Storage Disease Type III/genetics* ; Humans ; Mutation

OBJECTIVE: To explore the clinical and genetic characteristics of a Chinese pedigree affected by glycogen storage disease (GSD) type Ia with gout as the first manifestation. METHODS: Clinical and biochemical data of the pedigree were collected. Available members of the pedigree were subjected to gene sequencing, and the result was analyzed by bioinformatics software. The pedigree was followed up for five years. RESULTS: The proband was a young female manifesting recurrent gout flare, hypoglycemia, and hypertriglyceridemia. One of her younger brothers also presented with dysplasia and hepatic adenoma. Gene sequencing revealed that the proband and her younger brother both harbored c.1022T>A (p.I1e341Asn) and c.230+5G>A compound heterozygous variants of the G6PC gene , which were inherited from their father and mother, respectively. Among these, the c.230+5G>A is an intron region variant which was unreported previously, and bioinformatics analysis showed that it may impact mRNA splicing of the gene. The proband was treated with raw corn starch, allopurinol, and fenofibrate. Gout was well controlled, and she had given birth to a baby girl without GSD. CONCLUSION GSD Ia should be considered among young gout patients with hypoglycemia and hepatomegaly, for which gene sequencing is warranted. GSD Ia has a good prognosis after comprehensive treatment with diet and medicine.
China ; Female ; Glycogen Storage Disease Type I ; Gout/genetics* ; Humans ; Hypoglycemia ; Male ; Pedigree ; Symptom Flare Up

OBJECTIVE: To explore the clinical features and genetic basis of a patient with glycogen storage disease type VI (GSD-VI). METHODS: Clinical data of the patient was collected. Genomic DNA was extracted from peripheral blood samples of the proband and his parents. Genetic variants were detected by using whole exome sequencing. Candidate variants were verified by Sanger sequencing followed by bioinformatics analysis. RESULTS: The proband presented fasting hypoglycemia, hepatomegaly, growth retardation, transaminitis, metabolic acidosis and hyperlactatemia. Liver biopsy indicated GSD. Novel compound heterozygous PYGL gene variants (c.2089A>G/c.158_160delACT) were detected in the proband. Compound heterozygosity was confirmed by Sanger sequencing of the patient's genomic DNA. Provean and MutationTaster predicted the two variants as deleterious and the variant sites are highly conserved. CONCLUSION The compound heterozygous variants (c.2089A>G/c.158_160delACT) of PYGL gene probably underlay the GSD in the patient. The two novel variants have expanded the spectrum of PYGL gene variants and provided the basis for genetic counseling of the family.
Child ; Family ; Genetic Testing ; Glycogen Storage Disease Type VI/genetics* ; Humans ; Mutation ; Whole Exome Sequencing

OBJECTIVETo detect potential mutation of the AGL gene in two siblings affected with glycogen storage disease type IIIa.

METHODSClinical data of the two siblings was collected and analyzed. Genomic DNA was extracted from peripheral venous blood samples from the patients and their parents. All exons and their flanking sequences of the AGL gene were subjected to PCR amplification and Sanger sequencing. Suspected mutation was verified in 75 healthy controls.

RESULTSThe main clinical features of the two siblings included hypoglycemia and hepatomegaly, along with markedly elevated liver and myocardial enzymes. Genetic analysis revealed that both siblings harbored compound heterozygous mutations c.1735+1G>T and c.959-1G>C of the AGL gene. Among these, the splicing mutation c.959-1G>C was a novel one with an allele frequency of <1%.

CONCLUSIONBased on their clinical features and genetic analysis, the siblings were diagnosed with glycogen storage disease type IIIa. The c.959-1G>C has enriched the spectrum of AGL gene mutations.

Adolescent ; Amino Acid Sequence ; Female ; Glycogen Debranching Enzyme System ; genetics ; Glycogen Storage Disease Type III ; genetics ; Humans ; Infant ; Male ; Mutation ; genetics ; Siblings

OBJECTIVEGlycogen debranching enzyme (AGL) plays an important role in complete degradation of the glycogen, and has two independent catalytic activities, i.e., those of alpha-1, 4-glucanotransferase (EC 2.4. 1.25) and amylo-1,6-glucosidase (EC 3.2. 1.33). A deficiency in activities of AGL causes excessive accumulation of glycogen with short branched outer chains and results in glycogen storage disease type III (GSD III; MIM #232 400), an autosomal recessive inborn disorder of glycogen metabolism. The present study aimed to investigate the mutation of AGL in 10 Chinese patients with GSD III.

METHODClinical and laboratory data of 10 patients with typical clinical manifestations of GSD III suggesting hypoglycemia, hyperlipidemia, increased creatine-phosphokinase and its isozyme were collected. The coding regions and their flanking introns of AGL gene of the 10 patients were amplified by PCR and analyzed by direct DNA sequencing. All the mutated alleles were confirmed by bidirectional DNA sequencing. The 3 novel splicing mutations were analyzed by restriction fragment length polymorphism (RFLP) in 50 healthy children (control). The 2 small deletions (c.408-411delTTTG, c.2717-2721delAGATC) were analyzed by fluorescent polymerase chain reaction and gene scan analysis to confirm the number of deleted bases.

RESULTThirteen different mutations were identified, including 4 splicing mutations (IVS6 + 1G > A, IVS6-1G > A, IVS14 + 1G > T, IVS26-2A > C), 5 nonsense mutations (R469X, R864X, S929X, R977X, Y1428X), 3 small deletions (c.408-411delTTTG, c.2717-2721delAGATC, c.2823delT) and 1 insert mutation (c.4234insT). Except for IVS14 + 1G > T, R864X, and R977X, the other 10 mutations are novel; 18 mutated alleles were identified in the 20 alleles (90%). IVS14 + 1G > T was the most frequently seen mutation, accounting for 5 of 20 (25%) alleles examined. None of homozygote and heterozygote of the 3 novel splicing mutations was found in the 50 healthy controls by RFLP analysis. With the fluorescent polymerase chain reaction and gene scan analysis, c.408411deTTTG mutation and c.2717-2721delAGATC mutation were confirmed to have 4 and 5 bases deletion respectively.

CONCLUSIONThirteen mutations were identified in the 10 cases with GSD III, with 10 novel mutations. IVS14 + 1G > T was a relatively common mutation. This study revealed the heterozygosity of AGL gene in Chinese patients with GSD III.

Adolescent ; Asian Continental Ancestry Group ; genetics ; Base Sequence ; Child ; Child, Preschool ; DNA Mutational Analysis ; Glycogen Debranching Enzyme System ; genetics ; Glycogen Storage Disease Type III ; genetics ; Humans

OBJECTIVEGlycogen-storage disease type II (GSD II, Pompe's disease) is an autosomal recessive disorder caused by a functional deficiency of acid alpha-glucosidase (GAA) that leads to glycogen accumulation within lysosomes in most tissues. The GAA gene is located to human chromosome 17q25 and contains 20 exons, 19 of which are coding. Clinically, patients with the severe infantile form of GSD II have muscle weakness and cardiomyopathy eventually leading to death before the age of two years. Patients with the juvenile or the adult form of GSD II present with myopathy with a slow progression over several years or decades. A broad genetic heterogeneity has been described in GSD II in Europe, South Africa, USA, Japan and Korea, however, the investigation has not been performed in the patients from the mainland of China. In this study, clinical analysis and mutation detection were done on Chinese patients.

METHODSTwo unrelated juvenile patients with late onset GSD II (one boy, 3 years old and one girl, 9 years old) were included in the study with the informed consents. The diagnosis was confirmed by alpha-glucosidase determination in cultured fibroblasts. In addition, their clinical presentation, laboratory findings, electrophysiologic studies and muscle biopsy findings were analyzed in detail. Genomic DNA samples were extracted from fibroblasts of the probands, from peripheral blood of their parents and 50 unrelated, normal individuals. All the coding 19 exons and exon-intron boundaries of GAA were detected in the proband by polymerase chain reaction (PCR) and direct sequencing.

RESULTSOne patient presented decrease of muscle strength, limb-girdle hypotonia, the other patient presented reduced muscle volumes and respiratory problems. Both had increased CPK value, myopathic pattern on EMG; vacuoles on muscle biopsy, and deficiency of 1, 4-alpha-glucosidase activity. After 1 year follow up, the girl died after pneumonia at 10 years of age. One patient was found to be compound heretozygote for the novel mutation Arg702His, and the previously reported mutation Pro266Ser, which was reported in Korean population, with the late-onset phenotype. Two novel missense mutations Thr711Arg, Val723Met were found on the other patients.

CONCLUSIONSThree mutations identified in the patient were new missense mutations causing late onset GSD II, which had not been reported elsewhere before.

Child ; China ; Female ; Glucan 1,4-alpha-Glucosidase ; deficiency ; genetics ; Glycogen ; genetics ; metabolism ; Glycogen Storage Disease Type II ; enzymology ; genetics ; Humans ; Male ; Mutation ; Mutation, Missense ; Phenotype ; Young Adult