腓骨肌萎缩症X型临床、电生理及Connexin 32新突变一例

目的报告1例X连锁型腓骨肌萎缩症(CMTX),探讨其临床表现、电生理特点和连接蛋白32(Cx32)基因突变特点。方法对1例临床诊断CMT患者进行详细的病史采集和临床查体,分析其电生理和神经活检检查结果,同时进行周围髓鞘结构蛋白22(PMP22)基因重复和Connexin32(Cx32)基因突变检测。结果患者临床表现为经典的遗传性感觉运动神经病,肌电图检查提示脱髓鞘损害伴轴索损害,同时出现传导阻滞;神经活检示脱髓鞘性周围神经损害;基因检测发现Cx32基因编码序列第414位碱基发生单碱基错义突变(414C>G),造成其编码的第138位的氨基酸由丝氨酸突变为精氨酸(Ser138Arg)。结论 414C>G突变为Cx32基因新突变,国内外文献未见报道。该基因型没有产生特殊的临床表现,但电生理表现为脱髓鞘为主的混合性周围神经病变,且具有传导阻滞的特点。Cx32基因不同的突变位点和形式可能是导致CMTX临床异质性的原因之一。     

X连锁Charcot-Marie-Tooth病1型六个家系的病理和基因突变特点

目的 报道6个X连锁Charcot-Marie-Tooth病1型(CMTX1)家系的神经病理和基因型改变特点.方法 6个CMTX1家系的先证者均为男性,发病年龄11 ～24岁,出现下肢远端为主的肌无力、腱反射减低和轻度感觉减退.先证者1伴随发作性白质脑病,先证者5伴随小脑性共济失调.12名家系成员也出现周围神经损害症状,另7名存在高弓足或腱反射减低.对6例先证者行腓肠神经活体组织检查,并对6例先证者、8名受累家庭成员和10名无症状家系成员及50名健康女性进行缝隙连接蛋白32( Cx32)基因测序.结果 6例先证者有髓神经纤维出现轻-中度减少伴轴索再生变性,5例出现薄髓鞘神经纤维,其中3例伴洋葱球样结构,2例伴炎细胞浸润.6个家系的Cx32基因存在5种新突变和1种同义突变,即L20T、I127F、D178G、A197V错义突变,403_404T insT插入突变和L10L沉默突变,10名无症状家系成员中有4名女性为携带者,6名男性和健康对照均没有这些基因突变.结论 该组CMTX1患者的周围神经病理改变以慢性轴索损害为主,Cx32基因较多新突变的出现提示我国CMTX1患者具有个体突变特点.     

腓骨肌萎缩症CMTX1型的间隙连接蛋白32基因突变检测

目的检测无基因重复的腓骨肌萎缩症患者间隙连接蛋白32(connexin32,Cx32)基因的突变情况。方法应用变性高效液相色谱(DHPLC)结合混合样品池法和脱氧核糖核酸(DNA)序列测定对1个临床可疑的X连锁显性遗传的腓骨肌萎缩症CMTX1型家系的先证者和15名家庭成员及60名家系外健康对照者进行Cx32基因外显子2的基因编码区突变检测,分3个片段扩增其基因编码区全长。结果先证者在片段2的DHPLC中发现杂合双峰,经DNA序列测定证实其Cx32外显子2发生Leu89Pro(266T→C)错义突变;家系内其他4例发病者和5名未发病者Cx32外显子2都有与先证者一致的DHPLC杂合双峰。60名健康对照者中未发现上述改变。结论Leu89Pro是该家系的致病性突变。该突变体的致病机制如何,有待于做进一步研究。     

X连锁腓骨肌萎缩症Cx32基因的突变、临床和电生理特点

目的 分析X连锁腓骨肌萎缩症（CMTX）患者Cx32基凶的突变及其临床表现和电生理特点、方法应用多聚酶链反应一单链构象多态性分析结合DNA直接测序的方法,对24例无周围髓鞘蛋白（PMP）22基因大片段重复突变,家系中无男传男的腓骨肌萎缩症（CMT）先证者进行Cx32基因的突变分析;对先证者及其家系内患者进行临床和电生理检查。结果 在6个X连锁遗传家系和1例散发患者中发现了7个不同的Cx32基因突变,其中4个家系临床分型为CMTI型,2个家系为CMT中间型,散发病例为CMT1型检测到有Cx32基因突变的家系成员共38例,其巾男性20例,全部为CMTX患者;女性18例,其中6例为CMTX患者,12例为无临床症状的携带者;26例患者均为周围神经轻、中度受累。结论 CMTX的遗传方式可为X连锁显性、X连锁隐性遗传,也可为散发。根据临床和电生理特点分为CMTI型或CMT中间型,多为周围神经轻、中度受累,男性患者的症状通常较女性重。在没有检测到PMP22基因大片段重复突变和无男传男的CMT家系中应首先进行Cx32基因突变分析。     

腓骨肌萎缩症电生理、病理和基因定位研究

目的研究腓骨肌萎缩症(CMT)临床特征、基因测定、病理及神经电生理检查在其诊断和分型中的价值。方法收集50例CMT患者临床资料,对其进行肌电图检查及腓肠神经活检,并采用PCR技术直接测序进行基因突变分析。结果 40例CMT患者双下肢运动及感觉传导速度减慢(双胫、腓总神经为15~28 m/s,腓肠神经为12~30 m/s),10例双下肢未引出反应电位;50例正中神经运动及感觉传导速度亦减慢分别为19~48 m/s和20~52 m/s。CMT患者神经传导速度减慢的程度和临床表现的严重程度并不平行。腓肠神经活检符合慢性脱髓鞘部分伴轴索改变性周围神经病。PMP22、Cx32、MPZ、MFN2、GDAP1致病基因的突变分析发现14例患者存在PMP22基因的大片段重复突变(28%),13例患者存在Cx32基因的点突变(26%),4例患者存在MPZ基因的点突变(8%),3例患者存在MFN2基因的点突变(6%),未发现GDAP1基因的突变,16例患者未检测出上述基因突变。结论电生理、病理、基因测定在CMT的诊断及分型中有重要价值。     

突变缝隙连接蛋白32在X连锁Charcot-Marie-Tooth病1型患者的外周血管内皮细胞异常表达

目的 观察突变缝隙连接蛋白32( Cx32)在X连锁的Charcot-Marie-Tooth病1型(CMTX1)患者血管内皮细胞的表达规律。方法 对3例经Cx32基因检查证实的CMTX1患者（突变位点分别为c.379A＞T、c.533A＞G和c.590C＞T点突变）进行腓肠神经活体组织检查,同时取非CMTXI患者的神经作为对照。以第Ⅷ因子、缝隙连接蛋白40和Cx32单克隆抗体为一抗,对患者及对照者标本中的神经滋养血管进行免疫荧光标记。同时构建携带上述3个点突变的以增强型绿色荧光蛋白(enhanced green fluorescence protein,EGFP)为报告基因的重组质粒pEGFP-N1-CX32质粒,转染至HeLa细胞,并进行Cx32和内质网标志蛋白葡萄糖调节蛋白78免疫荧光染色,以观察Cx32蛋白在HeLa细胞的分布规律。结果 Cx32蛋白呈一定间隔规律性点状表达于对照组血管内皮细胞间的缝隙连接部位,与Cx40蛋白共表达;3例Cx32基因突变患者的血管内皮细胞膜的Cx32蛋白表达显著减少。细胞转染显示c.379A＞T突变的Cx32蛋白主要以团块状蓄积在HeLa细胞的胞质内,c.533A＞G突变的Cx32蛋白仅有少量表达于核周,c.590C＞T突变的Cx32蛋白在胞膜上和胞质内均有点状分布,较野生型显著减少。3种突变的Cx32蛋白在HeLa细胞内的分布和内质网标记不重叠。结论 不同Cx32基因突变均可导致CMTX1的血管内皮细胞膜Cx32蛋白表达下降,该蛋白主要聚集在细胞的内质网外。     

腓骨肌萎缩症伴神经性耳聋一家系临床和分子遗传学分析

目的探讨一个X连锁腓骨肌萎缩症(CMTX)伴常染色体隐性遗传的神经性耳聋家系的临床特点并研究其分子遗传学病因。方法对9名家系成员进行详细的临床检查，先证者进行了神经肌电图、听觉诱发电位和神经活检，3名耳聋患者进行电测听检查。运用聚合酶链反应一单链构象多态性分析技术(PCR-SSCP)结合直接测序法进行间隙连接蛋白32(eonnexin32)的突变分析，直接测序法进行间隙连接蛋白26(connexin26)的突变分析。结果家系中3名腓骨肌萎缩症患者为X连锁显性遗传，3名神经性耳聋患者为常染色体隐性遗传，其中1名患者同时出现腓骨肌萎缩症和神经性耳聋的临床症状。CMTX由connexin32错义突变C223T(Arg75Trp)引起。耳聋症状与connexin32点突变无共分离现象，对connexin26直接测序亦未发现突变，耳聋的致病基因有待进一步探讨。结论该家系腓骨肌萎缩症和耳聋分别由不同基因突变引起，这种在一个家系中同时出现两种不同遗传方式，不同致病基因的遗传病罕有报道。     

腓骨肌萎缩症2A2A型家系的神经电生理及基因突变分析

目的探讨一个腓骨肌萎缩症(charcot-marie-tooth,CMT)家系的临床表现、神经电生理学和基因突变特点。方法收集家系先证者及其他成员的临床资料,对先证者进行神经电生理学检查和全外显子组基因测序,用Sanger测序技术对先证者及其家系进行突变位点验证。应用计算机软件预测突变位点氨基酸进化保守性和突变可能导致的蛋白质结构和功能变化,分析突变位点的性质。结果先证者儿童期发病,出现双下肢对称性肌肉无力伴跟腱反射消失及足部畸形,其母亲有类似症状。先证者神经电生理检查示运动和感觉神经纤维脱髓鞘及轴索性改变。基因检测发现先证者和母亲MFN2基因第11个外显子均检出c.1066A>G(p.T356A)杂合错义突变;先证者姐姐和父亲未检测到该突变。用PolyPhen-2和MutationTaster软件预测该突变为致病性,突变区域序列在不同物种间高度保守。结论儿童CMT2A2A患者的神经电生理、临床特点、发病机制及相关基因表型均有改变,此可为儿童CMT的临床诊断提供依据。     

基因重复的进行性腓骨肌萎缩症1A型临床与电生理研究

目的研究有基因重复的进行性腓骨肌萎缩症1A型(Charcot-Marie-Tooth病1A,CMT1A)临床与电生理特点。方法对来自21个家系的22名CMT1A病人临床特点进行总结,同时分析其电生理特征,包括肌电图(EMG)、运动神经传导速度(MCV)和感觉神经传导速度(SCV)。结果18例病人20岁以前发病;20例为散发;均具有肢体远端肌肉无力和萎缩、腱反射减弱或消失、足畸形和上肢姿势震颤等典型的临床表现,偶尔合并膝腱反射活跃、病理征阳性、脊柱侧弯、足部溃疡和眼震等。17/22的病人肌电图上出现纤颤、正相电位,18/22的病人运动单位电位时限延长。有基因重复的CMT1A病人正中神经MCV与无基因重复的CMT1A病人无显著性差异。20/22的病人下肢SCV引不出,2/3以上病人下肢MCV引不出。结论本组病人散发病例多,临床表现差异较大。电生理特点为下肢神经病变重于上肢,感觉神经病变重于运动神经。CMT1A病人虽然基因型相同,表现型却存在差异。     

头部震颤伴小脑萎缩一例临床表型及基因突变分析

目的通过对1例头部震颤伴小脑萎缩患者临床表型和基因检测结果进行综合分析,明确诊断疾病并探讨基因检测结果的解读方法。方法与结果采集1例30岁男性患者临床表型,进行二代基因测序和Sanger测序验证,通过中文人类表型标准用语、基因检索工具Phenomizer、Ensembl数据库、在线人类孟德尔遗传数据库相关信息,对基因检测结果进行解读。结果显示,患者存在脊髓小脑共济失调19型(SCA19型)致病基因KCND3基因杂合突变c.1057AG(p.Ser353Gly),其父母均未携带该突变基因;患者还存在帕金森病20型致病基因SYNJ1基因杂合突变c.4436CT(p.Thr1479Ile),其母携带该突变基因。表型相似度分析显示,患者表型与SCA19型一致,KCND3基因变异位点c.1057AG在不同物种同源基因中具有高度保守性。结论通过对患者临床表型和基因检测结果综合分析,KCND3基因杂合突变c.1057AG(p.Ser353Gly)为致病性突变。     

A NOVEL MUTATION OF CONNEXIN-32 GENE IN A CMTX ITALIAN FAMILY

X-linked Charcot-Marie-Tooth is an inherited motor and sensory neuropathy associated with mutations in GJB1, a gene on chromosome X coding for the gap junction protein "connexin 32" (Cx32). Cx 32 gene is expressed in both peripheral and central nervous system myelin.
We describe a family affected by X-linked CMT neuropathy with a novel point mutation in Cx32 gene, in which the mother, the putative carrier, and three affected sons were examined. The affected sons (32, 35, 38 yrs) presented a motor-sensory slowly progressive neuropathy mainly involving lower limbs. Nerve conduction study showed both axonal and demyelinating pattern of denervation. Evoked potentials indicated visual and brainstem auditory pathway involvement. The mother showed subclinical electrophysiological abnormalities in nerve conduction velocities.
By mutational analysis of GJB1 using SSCP and sequencing of candidate regions, a previously undescribed missense mutation in the exon 2, codon 151, was found. This mutation was due to a transversion (TAT-> TCT) leading to a Tyr->Ser substitution in the 2nd extracellular domain.
Our findings further stress the wide variability in the spectrum of Cx32 mutations associated to CMTX, making it worthwhile to deepen knowledge about genotypic–phenotypic interrelationship in this disease.     

Charcot‐Marie‐Tooth type X: unusual phenotype of a novel CX32 mutation

Background: X‐linked Charcot‐Marie‐Tooth disease (CMTX), caused by mutations in the gene encoding connexin32, is the second most common form of inherited demyelinating neuropathy, next to CMT 1A, and accounts for 10–20% of all hereditary demyelinating neuropathies. Aims of the study: To describe clinical and electrophysiological data of an Italian family carrying a novel mutation in the Cx32 gene. Patients and methods: Clinical, electrophysiological, and genetic findings of three patients carrying the Ser128Leu mutation in the intracellular domain of the Cx32 gene were reported. Brain MRI studies were also performed. Results: In our family the disease was characterized by a moderate‐to‐severe polyneuropathy affecting similarly males as well females. In the proband the phenotype was quite unusual in terms of late‐onset, rapidity of evolution and severity. Abnormal brain MRI in association with CNS symptoms were also observed. Both sons had also clinical evidence of CNS involvement. Conclusions: The Ser128Leu mutation in the Cx‐32 gene is a novel substitution, which has not been reported so far. This novel mutation could be added to the group of Cx‐32 mutations with CNS phenotypes. The identification of new CMTX causing mutations is a crucial step for carrier detection and pre‐symptomatic diagnosis.     

X-linked Charcot-Marie-Tooth disease: phenotypic expression of a novel mutation Ile127Ser in the GJB1 (connexin 32) gene

We report a family with X-linked dominant Charcot-Marie-Tooth disease (CMTX1). Three affected family members are described, who underwent detailed clinical, electrophysiological, molecular genetic, and histopathological studies. A novel isoleucine at position 127 with serine (Ile127Ser) mutation in the gap junction protein beta 1 (GJB1) gene was detected. The electrophysiological findings were consistent with a primary demyelinating neuropathy with secondary axonal loss and support this model of disease progression. All patients having the CMT phenotype and intermediate conduction velocities who are negative for CMT1A duplication/hereditary neuropathy with liability to pressure palsies (HNPP) deletion, and whose family shows a dominant trait without male-to-male transmission, should be screened for CMTX1.     

Transient,recurrent, white matter lesions in X-linked Charcot-Marie-Tooth disease with novel connexin 32 mutation

BACKGROUND: X-linked hereditary demyelinating neuropathies (Charcot-Marie-Tooth Disease [CMTX]) caused by mutations in the connexin 32 (Cx32) gene account for approximately 10% to 20% of all hereditary demyelinating neuropathies. Mild subclinical central nervous system (CNS) involvement has been previously described, and CMTX patients with transient white matter lesions allied to CNS symptoms have very recently been described. This is of potential interest, as Cx32 is widely expressed in both peripheral nerve and the brain. PATIENTS: We describe a family with hereditary demyelinating neuropathy and transient CNS symptoms. For this study, family members underwent genotyping and detailed clinical, electrophysiological, and magnetic resonance imaging examination. RESULTS: We present a CMTX family with a novel mutation in the Cx32 gene. Affected family members show, in addition to the classic polyneuropathy, transient and reversible white matter lesions on magnetic resonance imaging scans, correlating similarly transient CNS symptoms. CONCLUSION: Patients with CMTX can present with transient CNS symptoms and marked white matter lesions on magnetic resonance imaging scans.     

Central visual, acoustic, and motor pathway involvement in a Charcot-Marie-Tooth family with an Asn205Ser mutation in the connexin 32 gene

BACKGROUND: X linked dominant Charcot-Marie-Tooth disease (CMT1X) is an inherited motor and sensory neuropathy that mainly affects the peripheral nervous system. CMT1X is associated with mutations in the gap junction protein connexin 32 (Cx32). Cx32 is expressed in Schwann cells and oligodendrocytes in the peripheral (PNS) and in the (CNS) respectively. METHODS: A CMT1X family with a Cx32 mutation was examined clinically and electrophysiologically to determine whether PNS, or CNS, or both pathways were affected. RESULTS: In a CMT1X family a novel mutation (Asn205Ser) was found in the fourth transmembrane domain of Cx32. The patients showed typical clinical and electrophysiological abnormalities in the PNS, but in addition visual, acoustic, and motor pathways of the CNS were affected subclinically. This was indicated by pathological changes in visually evoked potentials (VEPs), brainstem auditory evoked potentials (BAEPs), and central motor evoked potentials (CMEPs). CONCLUSIONS: These findings underscore the necessity of a careful analysis of CNS pathways in patients with CMT and Cx32 mutations. Abnormal electrophysiological findings in CNS pathway examinations should raise the suspicion of CMTX and a search for gene mutations towards Cx32 should be considered.     

Unusual electrophysiological findings in X-linked dominant Charcot-Marie-Tooth disease

X-linked Charcot-Marie-Tooth disease (CMTX) is the second most common form of Charcot-Marie-Tooth disease. Variable histopathological and nerve conduction velocity (NCV) results have suggested either a primary demyelinating or axonal polyneuropathy. We identified five individuals across three generations in a family with CMTX associated with a mutation in the gene coding for connexin 32. All individuals were studied by clinical neurological examination, DNA analysis, and nerve conduction studies. The proband (1174/KD) also underwent a sural nerve biopsy. As expected, all the affected males were more clinically affected than the females. All affected males and obligate female carriers exhibited some electrophysiological characteristics of demyelination. However, striking heterogeneity of nerve conduction velocities was seen. This family shows that CMTX is a heterogeneous and distinctly nonuniform demyelinating polyneuropathy, the severity of which varies with sex and age. Such electrophysiological variability is unique among hereditary neuropathies.     

Clinical and molecular studies in a family with probable X-linked dominant Charcot-Marie-Tooth disease involving the central nervous system.

OBJECTIVE: To investigate the clinical and molecular characteristics of an apparently X-linked dominant form of Charcot-Marie-Tooth (CMT) disease in a family with central nervous system involvement and additional features. BACKGROUND: Charcot-Marie-Tooth disease may be inherited as an autosomal dominant, autosomal recessive, or X-linked trait. In the X-linked dominant form of CMT, females demonstrate milder clinical and electrophysiological features compared with their male relatives. METHODS: Clinical and related examinations were performed in 4 affected individuals from a family with a novel form of CMT affecting males more severely than females. DNA analysis of the connexin 32 (Cx32) gene and proteolipid protein (PLP) gene was performed. We genotyped 3 members of the family to determine which regions of the X chromosome were inherited discordantly in the affected and unaffected brothers. RESULTS: Clinical studies revealed significant spasticity, hyperreflexia, and delayed central conduction, in addition to peripheral neuropathy. Nerve conduction velocities were slower in the affected males than in the affected females. Direct DNA sequencing of the Cx32 coding region and neural-specific promoter were normal. A PLP null mutation was excluded. Levels of very long chain fatty acids were normal. Genotyping studies of the X chromosome supported X-linked inheritance of the neuropathy. CONCLUSIONS: This family differs from others with hereditary motor and sensory neuropathic diseases by the presence of upper motor neuron signs and additional features. The clinical features and inheritance pattern are consistent with X-linked dominant inheritance or autosomal dominant inheritance.     

Charcot-Marie Tooth type X (CMTX) disease: clinical and genetic characteristics of eleven patients

Charcot-Marie-Tooth type X disease (CMTX) is the second most frequent inherited neuropathy, after CMT1A type associated with 17p11.2-p12 duplication. CMTX is inherited as X dominant trait and is caused by point mutations in Cx32 gene. In the study the first Polish group of 11 patients with CMTX from 4 families is presented. The following four mutations were found in Cx32 gene: Gly110Asp, Val 152 Asp, Arg 183 His and Glu 208 Gly. CMTX is characterized by X dominant trait of inheritance, a mild clinical course in affected females and slowly progressive atrophy and weakness of distal limb muscles. Both electrophysiological and sural nerve biopsy studies show axonal changes with secondary demyelination.