摘要目的 报道1个伴永久性肌病的周期性麻痹性副肌强直汉族家系的临床特点,并对其热点基因进行突变分析.方法 收集1个伴永久性肌病的周期性麻痹性副肌强直汉族家系的病史、临床特点,并于发作间期对部分患者进行常规肌电图检查、运动和冷水试验;对该家系中部分成员成人骨骼肌钠通道的仅亚单位(SCN4A)基因进行突变分析.结果 该家系4代中有15例成员患病,同时表现出正常血钾性周期性麻痹和副肌强直的特点,临床表现严重,中年后进展为进展性肌病.肌电图可见强直放电,运动试验复合肌肉动作电位(CMAP)波幅下降>4JD%,冷水试验CMAP下降大于运动实验.基因分析发现SCN4A基因存在Met1592Val突变.结论 该家系为常染色体显性遗传,外显率完全,表现型与基因型的关系与国外报道大致一致,但表现型更为严重;肌电图运动试验和冷水试验是一种简单、可靠、易行的辅助诊断方法.周期性麻痹和副肌强直可由同一个突变所引起,对于伴有永久性肌病的周期性麻痹性副肌强直患者SCN4A Met1592Val可作为筛查对象.

abstractsObjective To report clinical symptoms of a Chinese pedigree of familial paramyotonia congenital (PMC) with progressive myopathy (PM), and investigate the mutations of hot spots in the adult skeletal muscle sodium channel α-subunit (SCN4A). Methods The medical history and clinical phenotype of the patients from this large family with PMC were collected. Insertional and spontaneous activity were recorded by routine electromyograph (EMG), and the exercise test (ET) and cool water test were also performed on some patients during episodes. The mutations of SCN4A were screened by PCR-SSCP and DNA sequencing in affected and unaffected members. Results The family is a four-generation kindred with 15 members affected by severe, homogeneous paralysis periodiea paramyotoniea pheuotype. The onset was early, and almost all patients developed severe progressive myopathy by middle age. Routine EMG shows myotonia discharge in all affected subjects. The compound remarkably motor action potential (CMAP) decreased more than 40% after ET with greater decreases in cool water test than in ET. The mutation screening study revealed a missense mutation (Met1592Val) in SCN4A in patients. Conclusions Autosomal dominant inheritance pattern with complete penetrance was observed in this family. The phenotype is in accord with that reported in other ethnic populations with more severe symptoms. The ET and cool water tests may be used as an easy and reliable diagnostic method. Our research supports that periodic paralysis and paramyotonia can be caused by the same mutation in SCN4A. Mutation Met1592Val is a hotspot for mutation screening in patients with PMC accompanied by PM in the Chinese population.