Abstract
Muscle phosphorylase b kinase (PHK) deficiency (glycogenosis type VIII) is a rare disorder caused by mutations in the PHKA1 gene encoding the alpha(M) subunit of PHK. Only 5 patients with molecular defects in the X-linked PHKA1 gene have been described until now, and they all presented with exercise intolerance. Here, we report a patient with a new mutation in the PHKA1 gene who presented with PHK deficiency, cognitive impairment, but no overt myopathy. This report supports the concept that PHK deficiency is a mild metabolic myopathy and suggests that PHK mutations may interfere with normal brain function.
Copyright 2009 Elsevier B.V. All rights reserved.
MeSH terms
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Adult
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Amino Acid Sequence / genetics
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Biopsy
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Brain / enzymology
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Brain / physiopathology
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Codon, Nonsense / genetics
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Cognition Disorders / enzymology*
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Cognition Disorders / genetics*
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Cognition Disorders / physiopathology
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Creatine Kinase / blood
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DNA Mutational Analysis
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Electromyography
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Exercise Tolerance / genetics
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Glycogen Storage Disease Type V / complications
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Glycogen Storage Disease Type V / enzymology*
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Glycogen Storage Disease Type V / genetics*
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Humans
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Intellectual Disability / enzymology
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Intellectual Disability / genetics
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Intellectual Disability / physiopathology
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Intelligence / genetics
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Male
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Muscle Weakness / enzymology
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Muscle Weakness / genetics
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Muscle, Skeletal / enzymology
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Muscle, Skeletal / physiopathology
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Phosphorylase Kinase / deficiency*
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Phosphorylase Kinase / genetics*
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Protein Subunits / genetics
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Protein Subunits / metabolism
Substances
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Codon, Nonsense
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Protein Subunits
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Phosphorylase Kinase
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Creatine Kinase