Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0019209 (hepatomegaly)
 5,798 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

X-linked liver glycogenosis (XLG) due to liver phosphorylase kinase (PHK) deficiency is the most frequent liver glycogen storage disease. The affected patients present in early childhood with hepatomegaly and growth retardation. We isolated and determined the structure of human liver alpha subunit of PHK (PHKA2) cDNA. The 3705 base pair open reading frame encodes a polypeptide of 1235 amino acid residues, and the deduced amino acid sequence shows 93 and 68% homology to that of rabbit liver alpha subunit of PHK and human muscle alpha subunit of PHK, respectively. We identified a missense mutation, a valine substitution for glycine at amino acid 193, in the PHKA2 gene of a family with XLG.
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PMID:Isolation of cDNA encoding the human liver phosphorylase kinase alpha subunit (PHKA2) and identification of a missense mutation of the PHKA2 gene in a family with liver phosphorylase kinase deficiency. 754 48

X-linked liver glycogenosis type II (XLG II) is a recently described X-linked liver glycogen storage disease, mainly characterized by enlarged liver and growth retardation. These clinical symptoms are very similar to those of XLG I. In contrast to XLG I patients, however, XLG II patients do not show an in vitro enzymatic deficiency of phosphorylase kinase (PHK). Recently, mutations were identified in the gene encoding the liver alpha subunit of PHK (PHKA2) in XLG I patients. We have now studied the PHKA2 gene of four unrelated XLG II patients and identified four different mutations in the open reading frame, including a deletion of three nucleotides, an insertion of six nucleotides and two missense mutations. These results indicate that XLG II is due to mutations in PHKA2. In contrast to XLG I, XLG II is caused by mutations that lead to minor structural abnormalities in the primary structure of the liver alpha subunit of PHK. These mutations are found in a conserved RXX(X)T motif, resembling known phosphorylation sites that might be involved in the regulation of PHK. These findings might explain why the in vitro PHK enzymatic activity is not deficient in XLG II, whereas it is in XLG I.
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PMID:X-linked liver glycogenosis type II (XLG II) is caused by mutations in PHKA2, the gene encoding the liver alpha subunit of phosphorylase kinase. 873 33

We identified a novel mutation in the glycogen phosphorylase gene (PGYL) in a Chinese patient with glycogen storage disease (GSD) type VI. The patient presented with gross hepatomegaly since the age of two without history of any hypoglycemic attack. Otherwise, he was largely asymptomatic. Liver tissue enzyme assays revealed a mild deficiency of total glycogen phosphorylase. Both PGYL and PHKA2 genes were sequenced. The patient was homozygous of a missense mutation G233D in PGYL. This location forms a hairpin turn secondary structure and the small glycine residue is completely conserved in all the orthologous proteins from Escherichia coli to mammals. This is the sixth reported mutation of this form of GSD.
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PMID:A novel mutation (G233D) in the glycogen phosphorylase gene in a patient with hepatic glycogen storage disease and residual enzyme activity. 1280 46

Phosphorylase kinase-deficient liver glycogenosis manifests in infancy with hepatomegaly, growth retardation, and elevated plasma aminotransferases and lipids. It can be caused by mutations in three different genes of phosphorylase kinase subunits: PHKA2, PHKB, and PHKG2. It is usually a benign condition, often with complete resolution of symptoms during puberty. A minority of patients displays a more severe phenotype with symptomatic fasting hypoglycemia and abnormal liver histology that may progress to cirrhosis. Three patients with liver cirrhosis in childhood analyzed previously all had PHKG2 mutations. This suggested that this genotype may generally cause a more severe clinical manifestation, but to date PHKG2 mutations have been identified in only seven patients. Here, we report mutation analysis in three new patients with liver phosphorylase kinase deficiency and recurrent hypoglycemia, liver fibrosis, and lack of glucagon response but no overt cirrhosis. In all three patients, PHKG2 mutations were found (H89fs[insC], E157K, D215N, W300X). Three of these mutations are novel, bringing the total number of distinct human PHKG2 mutations to 11, found in 10 patients. We conclude that liver phosphorylase kinase deficiency with a severe phenotype, with or without cirrhosis, is indeed often caused by PHKG2 mutations. These patients require active measures to maintain normoglycemia (raw cornstarch, nocturnal tube feeding), which may also alleviate growth retardation and the development of abnormal liver histology.
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PMID:Severe phenotype of phosphorylase kinase-deficient liver glycogenosis with mutations in the PHKG2 gene. 1293 Sep 17

X-linked liver glycogenosis (XLG), also known as glycogen storage disease type-lXa, is characterized by hepatomegaly, abnormal liver functions and growth retardation. It is caused by mutations in the PHKA2 gene that encodes the alpha-subunit of phosphorylase kinase (PHK). XLG can be divided into two subtypes: XLG-I, with a deficiency in PHK activity in peripheral blood cells and the liver; and XLG-II, with normal PHK activity in vitro. This report describes two boys who presented with hepatomegaly and abnormal liver function. Pedigree analysis revealed them to be fifth-degree relatives, with the disease transmitted through undiagnosed grandfathers. Liver histology confirmed GSD diagnosis, and both cases had a deficiency in PHK activity in red blood cells and liver tissues. This is the first report of XLG-I in the ethnic-Chinese population in Taiwan. This report indicates that XLG may be undiagnosed or underestimated. A correct diagnosis is necessary for proper management and genetic counseling.
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PMID:X-linked liver glycogenosis in a Taiwanese family: transmission from undiagnosed males. 1985 67

Glycogen storage disease (GSD) due to a deficient hepatic phosphorylase system defines a genetically heterogeneous group of disorders that mainly manifests in children. We investigated 45 unrelated children in whom a liver GSD VI or IX was suspected on the basis of clinical symptoms including hepatomegaly, increased serum transaminases, postprandial lactatemia and/or mild fasting hypoglycemia. Liver phosphorylase and phosphorylase b kinase activities studied in peripheral blood cells allowed to suspect diagnosis in 37 cases but was uninformative in 5. Sequencing of liver phosphorylase genes was useful to establish an accurate diagnosis. Causative mutations were found either in the PYGL (11 patients), PHKA2 (26 patients), PHKG2 (three patients) or in the PHKB (three patients) genes. Eleven novel disease causative mutations, five missense (p.N188K, p.D228Y, p.P382L, p.R491H, p.L500R) and six truncating mutations (c.501_502ins361pb, c.528+2T>C, c.856-29_c.1518+614del, c.1620+1G>C, p.E703del and c.2313-1G>T) were identified in the PYGL gene. Seventeen novel disease causative mutations, ten missense (p.A42P, p.Q95R, p.G131D, p.G131V, p.Q134R, p.G187R, p.G300V, p.G300A, p.C326Y, p.W820G) and seven truncating (c.537+5G>A, p.G396DfsX28, p.Q404X, p.N653X, p.L855PfsX87, and two large deletions) were identified in the PHKA2 gene. Four novel truncating mutations (p.R168X, p.Q287X, p.I268PfsX12 and c.272-1G>C) were identified in the PHKG2 gene and three (c.573_577del, p.R364X, c.2427+3A>G) in the PHKB gene. Patients with PHKG2 mutations evolved towards cirrhosis. Molecular analysis of GSD VI or IX genes allows to confirm diagnosis suspected on the basis of enzymatic analysis and to establish diagnosis and avoid liver biopsy when enzymatic studies are not informative in blood cells.
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PMID:Liver glycogen storage diseases due to phosphorylase system deficiencies: diagnosis thanks to non invasive blood enzymatic and molecular studies. 2164 31

X-linked liver glycogenosis (XLG) is caused by a mutation in the PHKA2 gene which encodes the alpha subunit of phosphorylase kinase (PHK). Although XLG is not a rare disease, there have been no reports of PHKA2 mutations in Koreans. A 5-year-old boy presented with easy fatigability and hepatomegaly. Liver enzymes were increased and liver histology revealed deposition of glycogen. The PHK activity was markedly decreased compared to control. No amplification was observed at exon 8 of the PHKA2 gene, as a result of the deletion of exon 8. Sequence analysis revealed a hemizygous deletion in the region of exon 8 (c.717+781_864+225del1626). The patient was diagnosed as having XLG I. To the best of our knowledge, this is the first report of XLG I in Koreans.
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PMID:A novel PHKA2 gross deletion mutation in a Korean patient with X-linked liver glycogenosis type I. 2184 81

We found that the missense mutation p.Pro1205Leu in the PHKA2 gene is a common cause of hepatic phosphorylase-kinase deficiency in Dutch patients, suggesting a founder-effect. Most patients presented with isolated growth delay and diarrhea, prior to the occurrence of hepatomegaly, delaying diagnosis. Tetraglucoside excretion correlated with disease severity and was used to follow compliance. The clinical presentation and therapeutic requirements in the same mutation carriers were variable, and PhK deficiency necessitated tube-feeding in some children.
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PMID:Common mutation in the PHKA2 gene with variable phenotype in patients with liver phosphorylase b kinase deficiency. 2191 7

Liver phosphorylase b kinase (PhK) deficiency (glycogen storage disease type IX), one of the most common causes of glycogen storage disease, is caused by mutations in the PHKA2, PHKB, and PHKG2 genes. Presenting symptoms include hepatomegaly, ketotic hypoglycemia, and growth delay. Clinical severity varies widely. Autosomal recessive mutations in the PHKG2 gene, which cause about 10-15% of cases, have been associated with severe symptoms including increased risk of liver cirrhosis in childhood. We have summarized the molecular, biochemical, and clinical findings in five patients, age 5-16 years, diagnosed with liver PhK deficiency caused by PHKG2 gene mutations. We have identified five novel and two previously reported mutations in the PHKG2 gene in these five patients. Clinical severity was variable among these patients. Histopathological studies were performed for four of the patients on liver biopsy samples, all of which showed signs of fibrosis but not cirrhosis. One of the patients (aged 9 years) developed a liver adenoma which later resolved. All patients are currently doing well. Their clinical symptoms have improved with age and treatment. These cases add to the current knowledge of clinical variability in patients with PHKG2 mutations. Long term studies, involving follow-up of these patients into adulthood, are needed.
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PMID:Variability of disease spectrum in children with liver phosphorylase kinase deficiency caused by mutations in the PHKG2 gene. 2438 71

Glycogen storage disease type IX (GSD IX) is caused by a defect in phosphorylase b kinase (PhK) that results from mutations in the PHKA2, PHKB, and PHKG2 genes. Patients usually manifest recurrent ketotic hypoglycemia with growth delay, but some may present simple hepatomegaly. Although GSD IX is one of the most common causes of GSDs, its biochemical and genetic diagnosis has been problematic due to its rarity, phenotypic overlap with other types of GSDs, and genetic heterogeneities. In our report, a 22-month-old boy with GSD IX is described. No other manifestations were evident except for hepatomegaly. His growth and development also have been proceeding normally. Diagnosed was made by histologic examination, an enzyme assay, and genetic testing with known c.3210_3212del (p.Arg1070del) mutation in PHKA2 gene.
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PMID:Clinical, Biochemical, and Genetic Characterization of Glycogen Storage Type IX in a Child with Asymptomatic Hepatomegaly. 2615 1


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