| Is muscle glycogenolysis impaired in X-linked phosphorylase b kinase deficiency? | |
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MedLine Citation:
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PMID: 18401027 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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OBJECTIVE: It is unclear to what extent muscle phosphorylase b kinase (PHK) deficiency is associated with exercise-related symptoms and impaired muscle metabolism, because 1) only four patients have been characterized at the molecular level, 2) reported symptoms have been nonspecific, and 3) lactate responses to ischemic handgrip exercise have been normal. METHODS: We studied a 50-year-old man with X-linked PHK deficiency using ischemic forearm and cycle ergometry exercise tests to define the derangement of muscle metabolism. We compared our findings with those in patients with McArdle disease and in healthy subjects. RESULTS: Sequencing of PHKA1 showed a novel pathogenic mutation (c.831G>A) in exon 7. There was a normal increase of plasma lactate during forearm ischemic exercise, but lactate did not change during dynamic, submaximal exercise in contrast to the fourfold increase in healthy subjects. Constant workload elicited a second wind in all patients with McArdle disease, but not in the patient with PHK deficiency. IV glucose administration appeared to improve exercise tolerance in the patient with PHK deficiency, but not to the same extent as in the patients with McArdle disease. Lipolysis was higher in the patient with PHK deficiency than in controls. CONCLUSION: These findings demonstrate that X-linked PHK deficiency causes a mild metabolic myopathy with blunted muscle glycogen breakdown and impaired lactate production during dynamic exercise, which impairs oxidative capacity only marginally. The different response of lactate to submaximal and maximal exercise is likely related to differential activation mechanisms for myophosphorylase. |
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Authors:
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M C Ørngreen; H J Schelhaas; T D Jeppesen; H O Akman; R A Wevers; S T Andersen; H J ter Laak; O P van Diggelen; S DiMauro; J Vissing |
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Publication Detail:
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Type: Journal Article Date: 2008-04-09 |
Journal Detail:
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Title: Neurology Volume: 70 ISSN: 1526-632X ISO Abbreviation: Neurology Publication Date: 2008 May |
Date Detail:
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Created Date: 2008-05-13 Completed Date: 2008-06-11 Revised Date: 2008-11-21 |
Medline Journal Info:
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Nlm Unique ID: 0401060 Medline TA: Neurology Country: United States |
Other Details:
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Languages: eng Pagination: 1876-82 Citation Subset: AIM; IM |
Affiliation:
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Neuromuscular Research Unit 7611, Copenhagen University Hospital, Rigshospitalet, Blegdamsvej 9, DK-2100 Copenhagen, Denmark. rh10679@rh.dk |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Chromosomes, Human, X* Exercise Test Glycogen / metabolism Glycogen Storage Disease Type V / genetics, metabolism Glycogen Storage Disease Type VIII / genetics*, metabolism Glycogenolysis / genetics* Humans Lactic Acid / metabolism Male Middle Aged Muscle Weakness / genetics, metabolism Muscle, Skeletal / enzymology Oxidative Stress / genetics Phosphorylase Kinase / deficiency, genetics*, metabolism Physical Exertion / physiology Point Mutation* Protein Subunits / genetics, metabolism |
| Chemical | |
Reg. No./Substance:
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0/Protein Subunits; 50-21-5/Lactic Acid; 9005-79-2/Glycogen; EC 2.7.1.19/Phosphorylase Kinase |
| Comments/Corrections | |
Comment In:
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Neurology. 2008 May 13;70(20):1872-3
[PMID:
18474841
]
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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