Introduction

Mutations of the skeletal muscle sodium channel gene SCN4A are associated with several neuromuscular disorders including hyper/hypokaliemic periodic paralysis, paramyotonia congenita and sodium channel myotonia. These disorders are distinguished from dystrophic myotonias by the absence of progressive weakness and extramuscular systemic involvement.

Methods

We present an Italian family with 2 subjects carrying a p.Asn1180Ile mutation in SCN4A gene showing a peculiar clinical picture characterized by the association of myopathic features and myotonia.

Results

The clinical, electromyographic and histological findings of these patients are reported. The possible pathogenicity of the mutation was tested by three different software, all giving positive results.

Discussion

This is the first report of a dominant, heterozygous mutation in SCN4A causing a complex phenotype of non-congenital myopathy and myotonic syndrome. We suggest that, in patients with myotonia and myopathy not related to dystrophic myotonias, the sequence analysis of SCN4A gene should be performed.

中文翻译：

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p.Asn1180Ile 突变 SCN4A 基因在意大利肌病和强直综合征家族中的作用

介绍

骨骼肌钠通道基因SCN4A的突变与几种神经肌肉疾病有关，包括高/低钾性周期性麻痹、先天性副肌强直和钠通道肌强直。这些疾病与营养不良性肌强直的区别在于没有进行性虚弱和肌肉外全身受累。

方法

我们介绍了一个意大利家庭，其中 2 名受试者在SCN4A基因中携带 p.Asn1180Ile 突变，显示出以肌病特征和肌强直相关为特征的特殊临床表现。

结果

报告了这些患者的临床、肌电图和组织学发现。三种不同的软件测试了突变的可能致病性，均给出了阳性结果。

讨论

这是SCN4A中的显性杂合突变导致非先天性肌病和强直综合征的复杂表型的第一份报告。我们建议，对于与营养不良性肌强直无关的肌强直和肌病患者，应进行SCN4A基因序列分析。