Paramyotonia congenita: genotype to phenotype correlations in two families and report of a new mutation in the sodium channel gene

@article{Plassart1996ParamyotoniaCG,
  title={Paramyotonia congenita: genotype to phenotype correlations in two families and report of a new mutation in the sodium channel gene},
  author={Emmanuelle Plassart and Bruno Eymard and L. Maurs and Jean Jacques Hauw and Olivier Lyon‐Caen and Michel Gustave Jules Fardeau and Bertrand Fontaine},
  journal={Journal of the Neurological Sciences},
  year={1996},
  volume={142},
  pages={126-133}
}

Hyperkalemic periodic paralysis and paramyotonia congenita caused by a de novo mutation in the SCN4A gene

The case of a 17-year-old boy who presented with both hyperkalemic periodic paralysis and paramyotonia congenita is reported, with a molecular analysis of the SCN4A gene revealed a heterozygous T>C transition at nucleotide 2078, leading to an Ile693Thr mutation.

Clinical, electrophysiological, and molecular genetic studies in a new family with paramyotonia congenita

This study provides further evidence that exon 24 in SCN4A is a hot spot for paramyotonia mutations and this has implications for a DNA based diagnostic service.

Phenotypic variation of Val1589Met mutation in a four-generation Chinese pedigree with mild paramyotonia congenitia: case report.

Four generations of a Chinese family with a mild form of paramyotonia congenital was characterized in phenotype and genotype, indicating that family, individual, genetic or environmental factors influence symptoms.

Focal and abnormally persistent paralysis associated with congenital paramyotonia

It is hypothesised that the V1293I mutation may also alter the slow inactivation in specific conditions, for example, prolonged cold exposure or prolonged and intensive exercise.

Thr1313Met mutation in skeletal muscle sodium channels in a Japanese family with paramyotonia congenita.

A 37-year-old Japanese woman was referred from another clinic to confirm the diagnosis of myotonia congenita, the prevalence of which is very low in Japan, was diagnosed based on their clinical features and DNA analysis results.

Severe infantile hyperkalaemic periodic paralysis and paramyotonia congenita: broadening the clinical spectrum associated with the T704M mutation in SCN4A

Evidence that this mutation at codon 704 (T704M) in exon 13 of the skeletal muscle voltage gated sodium channel gene (SCN4A) is a common cause of hyperPP/PMC is supported.

Hypokalaemic periodic paralysis type 2 caused by mutations at codon 672 in the muscle sodium channel gene SCN4A.

A complete penetrance in men and women, an early age at onset, postcritic myalgias and an increased number and severity of attacks induced by acetazolamide are observed in a large hypoPP family carrying an SCN4A mutation.
...

References

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Sodium channel mutations in acetazolamide‐responsive myotonia congenita, paramyotonia congenita, and hyperkalemic periodic paralysis

This report summarizes the sodium channel mutation analysis in 25 families with hyperKPP and reports the putative disease-causing mutation in acetazolamide-responsiveMyotonia congenita, a related disease in which myotonia is worsened by potassium but in which episodic weakness does not occur.

Sodium channel mutations in paramyotonia congenita and hyperkalemic periodic paralysis

Five other HYPP and PC families have been ascertained, and previously reported sodium channel mutations have been identified in each, and an additional mutation is reported, a leucine ‐ arginine substirution in the ss segment of domain 4 (L1433R), that results in the PC phenotype.

Paramyotonia congenita without paralysis on exposure to cold: a novel mutation in the SCN4A gene (Val1293Ile).

Three German families with PC without cold paralysis are presented, evidence that the disorder is linked to the SCN4A gene is provided and a novel SCN 4A mutation (Val1293Ile) segregating in these families is reported.

Mutations in the Muscle Sodium Channel Gene (SCN4A) in 13 French Families with Hyperkalemic Periodic Paralysis and Paramyotonia Congenita: Phenotype to Genotype Correlations and Demonstration of the Predominance of Two Mutations

Recurrent mutations of SCN4A may contribute to the predominance of these two mutations in the French population by contributing to the severity of myotonia and its permanence were variable.

Hyperkalemic periodic paralysis

A novel procedure is described, using ligase chain reaction (LCR), to simultaneously identify two different point mutations and one rare, apparently benign polymorphism that results in a nonconservative amino acid substitution in hyperkalemic periodic paralysis.

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The findings in the present report indicate that myotonia fluctuans belongs to a third type of sodium channel disorder, and further work is needed to understand the complex genotype-phenotype correlations in sodium channel disorders.

Molecular genetic and genetic correlations in sodium channelopathies: lack of founder effect and evidence for a second gene.

The results indicate that dinucleotide-repeat haplotypes are not predictive of allelic heterogeneity in sodium channelopathies, contrary to previous suggestions, and identifies a HyperPP pedigree in which the dominant disorder was not linked to the sodium-channel gene.

Sodium channel mutations in paramyotonia congenita exhibit similar biophysical phenotypes in vitro.

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Findings help to explain the phenotypic differences between HYPP and PC at the molecular and biophysical level and contribute to the understanding of Na+ channel structure and function.