Abstract
We report a 4-generation Turkish family with 10 affected members presenting with myotonia and potassium- and exercise-induced paralytic attacks. The clinical presentation was neither typical for the chloride channel myotonias Thomsen and Becker nor for the separate sodium channel myotonia entities potassium-aggravated myotonia, paramyotonia congenita, and hyperkalemic periodic paralysis. It is best described by a combination of potassium-aggravated myotonia and hyperkalemic periodic paralysis. We excluded exonic chloride channel mutations including CLCN1 exon deletion/duplication by MLPA. Instead we identified a novel p.N440K sodium channel mutation that is located at the inner end of segment S6 of repeat I. We discuss the genotype phenotype relation.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Acetazolamide / therapeutic use
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Anti-Arrhythmia Agents / therapeutic use
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Anticonvulsants / therapeutic use
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Chloride Channels / genetics*
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Humans
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Hyperkalemia / complications*
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Hyperkinesis / complications*
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Hyperkinesis / physiopathology
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Muscle Weakness / etiology
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Muscle Weakness / physiopathology
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Muscle, Skeletal / physiopathology
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Myotonia Congenita / drug therapy
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Myotonia Congenita / etiology
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Myotonia Congenita / genetics*
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Paralysis / etiology
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Paralysis / physiopathology
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Pedigree
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Segmental Duplications, Genomic
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Sequence Deletion
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Severity of Illness Index
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Sodium Channels / genetics*
Substances
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Anti-Arrhythmia Agents
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Anticonvulsants
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CLC-1 channel
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Chloride Channels
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Sodium Channels
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Acetazolamide
Supplementary concepts
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Potassium aggravated myotonia