广西地区一家系先天性肌强直的临床资料和基因测定

目的探讨先天性肌强直(MC)一家系的临床特点及CLCN1基因部分外显子位点突变的情况。方法收集广西壮族自治区1例MC患者的临床及家系资料,提取家系成员和对照组(无血缘关系的健康体检者6名)的外周静脉血DNA,采用聚合酶链反应(PCR)扩增部分CLCN1基因,测定该基因第3、5、8、13、14、15、16号外显子序列,并对突变位点进行分析。结果 MC患者的6名家系和对照组成员的PCR扩增凝胶电泳分析表明,同一引物对应各样本条带均无显著差异;CLCN1基因被测序的第3、5、8、13、14、15、16号外显子序列均未发现有突变位点。结论该MC患者及家系中患者的MC致病基因位点未位于CLCN1基因这7个外显子序列上,需要对CLCN1基因全外显子序列进行检测分析。     

拉莫三嗪治疗Becker型先天性肌强直一例并文献复习

目的报道拉莫三嗪治疗1例Becker型先天性肌强直患者的疗效及安全性。方法与结果17岁男性患者,以四肢肌肉僵硬为首发症状,反复运动后症状减轻,血清肌酸激酶水平正常,基因检测提示存在CLCN1基因外显子11 c.1205C T(p.Ala402Val)及CLCN1基因外显子8 c.896T C(p.Val299Ala)错义突变,确诊为Becker型先天性肌强直;其母为CLCN1基因外显子11 c.1205C T(p.Ala402Val)、其父为CLCN1基因外显子8 c.896T C(p.Val299Ala)错义突变,确诊为Becker型先天性肌强直家系,其中CLCN1基因外显子8 c.896T C突变尚无报道。经拉莫三嗪连续治疗5年后肌强直症状长期缓解,且无任何药物不良反应。结论该例CLCN1基因外显子8 c.896T C错义突变进一步扩展了CLCN1基因突变谱。拉莫三嗪治疗效果良好,为Becker型先天性肌强直的治疗提供了新的思路。     

先天性肌强直一家系以及散发患者一例的临床、电生理、基因学研究

目的探讨先天性肌强直一家系和散发患者一例的临床、电生理、基因学特点。方法对先天性肌强直的一家系和一例散发的患者进行详细的临床资料搜集,对家系先证者以及相关的亲属进行CLCN1和SCN4A基因测序。结果家系中3代共有7例患者,其中5例患者以及一例无症状的家系成员接受了基因检测,结果发现5例患者携带CLCN1A298 T突变。在散发的患者中发现了S723 R错义杂合突变。结论 CLCN1基因A298 T突变是家系中先天性肌强直患者的致病突变,而S723R是否为散发患者的致病突变需要进一步明确。     

先天性肌强直一家系以及散发患者一例的临床、电生理、基因学研究

目的 探讨先天性肌强直一家系和散发患者一例的临床、电生理、基因学特点。方法 对先天性肌强直的一家系和一例散发的患者进行详细的临床资料搜集,对家系先证者以及相关的亲属进行CLCN1和SCN4A基因测序。结果 家系中3代共有7例患者,其中5例患者以及一例无症状的家系成员接受了基因检测,结果发现5例患者携带CLCN1 A298T突变。在散发的患者中发现了S723R错义杂合突变。结论 CLCN1基因A298T突变是家系中先天性肌强直患者的致病突变,而S723R是否为散发患者的致病突变需要进一步明确。     

先天性肌强直一家系CLCN1基因突变的研究

目的 探讨先天性肌强直一家系CLCN1基因的突变方式.方法 采用PCR方法对1个先天性肌强直家系中的先证者、其祖母、父母、弟弟以及100名无血缘关系健康对照者的CLCN1基因全部外显子进行DNA测序.结果 先证者CLCN1基因第8及11号外显子各发现1个错义突变,分别是c.950G→A和c.1205C→T.其父亲有c.950G→A突变,其母亲有c.1205C→T突变.其弟及100名健康对照者未见上述突变.结论 CLCN1基因c.950G→A和c.1205C→T错义突变是该家系CLCN1基因的致病性突变.     

常染色体隐性遗传早发性帕金森病1个家系临床特征及parkin基因突变分析

目的探讨1个常染色体隐性遗传早发性帕金森病（autosomal recessive early-onset parkinson-ism，AREP）家系的临床特征及parkin基因突变情况。方法对1个AREP家系2例患者的临床资料进行回顾性分析，同时应用DNA直接测序、限制性内切酶酶切、荧光半定量PCR等技术方法进行parkin基因的突变分析。结果该家系共2例患者，发病年龄轻，分别为22岁和23岁；病情进展相对缓慢，症状有波动，呈晨轻暮重，腱反射活跃；对小剂量多巴制剂反应良好。基因突变发现该家系存在parkin基因的复合杂合突变（第7号外显子杂合的G859T和第4外显子杂合缺失突变），其中G859T为新报道的点突变。结论我国的AREP家系有帕金森病的一般临床表现，又有其独特的临床特征，存在parkin基因的突变。     

骨骼肌钠通道α1亚基基因R1129Q新突变导致正常钾和低钾性周期性瘫痪一家系

目的 报道1个骨骼肌钠通道α1亚基(SCN4A)基因新突变导致的正常钾和低钾性周期性瘫痪家系的临床和病理改变特点.方法 本家系为常染色体显性遗传,共有9例患者,男性4例,女性5例,发病年龄7～25岁.5例患者为正常钾性周期性瘫痪,其中4例伴随肌强直症状;3例患者为低钾性周期性瘫痪;1例发作时血钾浓度不详.对先证者进行左肱二头肌活体组织检查.先证者和7例家系患者、3名无症状家系成员以及50名健康人行SCN4A基因测序.结果 先证者的肌纤维出现轻度肥大和萎缩,伴随核内移和肌纤维内空泡,部分肌纤维内氧化酶分布异常.所有患者均存在SCN4A基因的R1129Q突变,3名无症状家系成员以及50名健康对照无此突变.结论 SCN4A基因R1129Q新突变在同一家系内可以导致低血钾性和正常血钾性周期性瘫痪共存.     

骨骼肌钠通道α1亚基基因R1129Q新突变导致正常钾和低钾性周期性瘫痪一家系

目的 报道1个骨骼肌钠通道α1亚基(SCN4A)基因新突变导致的正常钾和低钾性周期性瘫痪家系的临床和病理改变特点.方法 本家系为常染色体显性遗传,共有9例患者,男性4例,女性5例,发病年龄7～25岁.5例患者为正常钾性周期性瘫痪,其中4例伴随肌强直症状;3例患者为低钾性周期性瘫痪;1例发作时血钾浓度不详.对先证者进行左肱二头肌活体组织检查.先证者和7例家系患者、3名无症状家系成员以及50名健康人行SCN4A基因测序.结果 先证者的肌纤维出现轻度肥大和萎缩,伴随核内移和肌纤维内空泡,部分肌纤维内氧化酶分布异常.所有患者均存在SCN4A基因的R1129Q突变,3名无症状家系成员以及50名健康对照无此突变.结论 SCN4A基因R1129Q新突变在同一家系内可以导致低血钾性和正常血钾性周期性瘫痪共存.     

周期性麻痹性副肌强直一家系临床及分子生物学特点

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.     

遗传性痉挛性截瘫2家系的临床特点与spastin基因突变分析

目的:探讨2个家系遗传3代以上常染色体显性遗传性痉挛性截瘫(AD-HSP)的临床特点及其与spastin基因突变的关系。方法:对2个AD-HSP家系进行详细的临床检查,总结所有患者临床特点,并应用PCR技术结合DNA序列分析方法,检测2家系先证者spastin基因的突变情况。结果:2家系中所有患者均具有HSP的典型表现,PCR-DNA序列分析2例先证者spastin基因的17个外显子均未发现有异常突变。结论:2家系HSP患者具有典型的AD-HSP临床表现,并非spastin基因外显子突变所致。     

Dosage effect of a dominant CLCN1 mutation: a novel syndrome

Multiple mutations in the CLCN1 gene coding for the voltage-gated chloride channel have been documented to cause myotonia congenita. We report a kindred featuring an index patient who possesses 2 copies of a dominantly inherited mutated CLCN1 allele with a resulting novel phenotypic presentation. The index patient is a boy who presented initially for evaluation at the age of 5 years with a 2-year history of gait problems. Both parents and 3 male siblings were entirely well. Examination revealed a striking diffuse muscular hypertrophy, diffuse mild to moderate weakness, Gower sign, percussion, and grip myotonia. Electromyography confirmed myotonia, and molecular analysis revealed 2 copies of the T310M mutation on the CLCN1 gene. Testing of family members revealed a normal neurological examination without clinical myotonia in all and electromyographic evidence of myotonia and a single copy of the T310M mutation in both parents and 2 siblings. Our kindred is the initial demonstration of the dosage effect of a dominant mutated allele in the CLCN1 gene.     

Thomsen or Becker myotonia? A novel autosomal recessive nonsense mutation in the CLCN1 gene associated with a mild phenotype

We describe a large Brazilian consanguineous kindred with 3 clinically affected patients with a Thomsen myotonia phenotype. They carry a novel homozygous nonsense mutation in the CLCN1 gene (K248X). None of the 6 heterozygote carriers show any sign of myotonia on clinical evaluation or electromyography. These findings confirm the autosomal recessive inheritance of the novel mutation in this family, as well as the occurrence of phenotypic variability in the autosomal recessive forms of myotonia.     

A missense mutation in the skeletal muscle chloride channel 1 (CLCN1) as candidate causal mutation for congenital myotonia in a New Forest pony

A 7-month-old New Forest foal presented for episodes of recumbency and stiffness with myotonic discharges on electromyography. The observed phenotype resembled congenital myotonia caused by CLCN1 mutations in goats and humans. Mutation of the CLCN1 gene was considered as possible cause and mutation analysis was performed. The affected foal was homozygous for a missense mutation (c.1775A>C, p.D592A) located in a well conserved domain of the CLCN1 gene. The mutation showed a recessive mode of inheritance within the reported pony family. Therefore, this CLCN1 polymorphism is considered to be a possible cause of congenital myotonia.     

Myotonia congenita in a large consanguineous Arab family: Insight into the clinical spectrum of carriers and double heterozygotes of a novel mutation in the chloride channel CLCN1 gene

The aims of this study were to (1) characterize the clinical phenotype, (2) define the causative mutation, and (3) correlate the clinical phenotype with genotype in a large consanguineous Arab family with myotonia congenita. Twenty‐four family members from three generations were interviewed and examined. Genomic DNA was extracted from peripheral blood samples for sequencing the exons of the CLCN1 gene. Twelve individuals with myotonia congenita transmitted the condition in an autosomal dominant manner with incomplete penetrance. A novel missense mutation [568GG>TC (G190S)] was found in a dose‐dependent clinical phenotype. Although heterozygous individuals were asymptomatic or mildly affected, the homozygous individuals were severely affected. The mutation is a glycine‐to‐serine residue substitution in a well‐conserved motif in helix D of the CLC‐1 chloride channel in the skeletal muscle plasmalemma. A novel mutation, 568GG>TC (G190S) in the CLCN1 gene, is responsible for autosomal dominant myotonia congenita with a variable phenotypic spectrum. Muscle Nerve, 2009     

Heterozygous CLCN1 mutations can modulate phenotype in sodium channel myotonia

Nondystrophic myotonias are characterized by muscle stiffness triggered by voluntary movement. They are caused by mutations in either the CLCN1 gene in myotonia congenita or in the SCN4A gene in paramyotonia congenita and sodium channel myotonias. Clinical and electrophysiological phenotypes of these disorders have been well described. No concomitant mutations in both genes have been reported yet. We report five patients from three families showing myotonia with both chloride and sodium channel mutations. Their clinical and electrophysiological phenotypes did not fit with the phenotype known to be associated with the mutation initially found in SCN4A gene, which led us to screen and find an additional mutation in CLCN1 gene. Our electrophysiological and clinical observations suggest that heterozygous CLCN1 mutations can modify the clinical and electrophysiological expression of SCN4A mutation.     

Clinical Diversity of SCN4A-Mutation-Associated Skeletal Muscle Sodium Channelopathy

Background and Purpose

Mutations of the skeletal muscle sodium channel gene SCN4A, which is located on chromosome 17q23-25, are associated with various neuromuscular disorders that are labeled collectively as skeletal muscle sodium channelopathy. These disorders include hyperkalemic periodic paralysis (HYPP), hypokalemic periodic paralysis, paramyotonia congenita (PMC), potassium-aggravated myotonia, and congenital myasthenic syndrome. This study analyzed the clinical and mutational spectra of skeletal muscle sodium channelopathy in Korean subjects.

Methods

Six unrelated Korean patients with periodic paralysis or nondystrophic myotonia associated with SCN4A mutations were included in the study. For the mutational analysis of SCN4A, we performed a full sequence analysis of the gene using the patients'' DNA. We also analyzed the patients'' clinical history, physical findings, laboratory tests, and responses to treatment.

Results

We identified four different mutations (one of which was novel) in all of the patients examined. The novel heterozygous missense mutation, p.R225W, was found in one patient with mild nonpainful myotonia. Our patients exhibited various clinical phenotypes: pure myotonia in four, and PMC in one, and HYPP in one. The four patients with pure myotonia were initially diagnosed as having myotonia congenita (MC), but a previous analysis revealed no CLCN1 mutation.

Conclusions

Clinical differentiating between sodium-channel myotonia (SCM) and MC is not easy, and it is suggested that a mutational analysis of both SCN4A and CLCN1 is essential for the differential diagnosis of SCM and MC.     

Co-segregation of DM2 with a recessive CLCN1 mutation in juvenile onset of myotonic dystrophy type 2

Myotonic dystrophy type 2 (DM2) is a common adult onset muscular dystrophy caused by a dominantly transmitted (CCTG)( n ) expansion in intron 1 of the CNBP gene. In DM2 there is no obvious evidence for an intergenerational increase of expansion size, and no congenital cases have been confirmed. We describe the clinical and histopathological features, and provide the genetic and molecular explanation for juvenile onset of myotonia in a 14-year-old female with DM2 and her affected mother presenting with a more severe phenotype despite a later onset of symptoms. Histological and immunohistochemical findings correlated with disease severity or age at onset in both patients. Southern blot on both muscle and blood samples revealed only a small increase in the CCTG repeat number through maternal transmission. Fluorescence in situ hybridization, in combination with MBNL1 immunofluorescence on muscle sections, showed the presence of mutant mRNA and MBNL1 in nuclear foci; the fluorescence intensity and its area appeared to be similar in the two patients. Splicing analysis of the INSR, CLCN1 and MBNL1 genes in muscle tissue demonstrates that the level of aberrant splicing isoforms was lower in the daughter than in the mother. However, in the CLCN1 gene, a heterozygous mutation c.501C>G p.F167L was present in the daughter's DNA and found to be maternally inherited. Biomolecular findings did not explain the unusual young onset in the daughter. The co-segregation of DM2 with a recessive CLCN1 mutation provided the explanation for the unusual clinical findings.