GJB1基因突变致腓骨肌萎缩症一家系

分析X-连锁腓骨肌萎缩症1型（X-linked Charcot-Marie-Tooth disease type 1, CMT1X）一家系的临床表现、电生理与突变基因特点。该家系为两代4人,共有2例CMT1X患者。先证者12岁起病,先证者母亲40岁起病,两者均表现为进行性肢体无力、萎缩,行走不稳。神经电生理检查均提示：四肢多发感觉运动神经损害（轴索损害为主并脱髓鞘）;多发肌肉呈神经源性损害。突变基因分析,先证者存在缝隙连接蛋白B1(gap junction protein Bata-1,GJB1)基因c.283 G>T(p.V95L)半合子突变,先证者母亲存在GJB1基因c.283 G>T(p.V95L),杂合突变。CMT1X是第二常见的腓骨肌萎缩症（Charcot-Marie-Tooth disease, CMT）类型,由GJB1基因突变引起,临床表现为进行性发展的周围神经病可合并中枢神经系统损害,基因检测有助诊断。     

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。     

腓骨肌萎缩症X1型1个家系的临床、电生理和Connexin32基因突变分析

目的观察腓骨肌萎缩症(CMT)X1型的临床、电生理特点和Connexin32(Cx32)基因突变情况.方法对1个无基因重复的临床可疑的CMTX1家系中的3例患者进行详尽的临床和神经电生理检查,并应用变性高效液相色谱结合混和样品池法和DNA序列测定对包括先证者在内的3名成员的Cx32基因进行突变检测.结果 该家系中的病人发生了Gly12Ser,50名正常人中未发现上述改变,提示该突变为致病性突变.家系中男性病人临床症状重于女性;电生理特点为脱髓鞘改变;同一病人的不同神经间存在异质性.结论 Gly12Ser突变可能导致原发性脱髓鞘性神经病,不伴有特殊的临床表现.     

线粒体融合蛋白2基因新突变导致的遗传性运动感觉性神经病6型一家系

目的 报道1个遗传性运动感觉性神经病6型家系的临床表现、病理改变以及基因突变特点。方法 先证者男性,15岁。患者5岁出现双下肢无力,症状进行性加重,伴随出现双足跟腱挛缩;11岁开始出现慢性进行性视力下降;12岁出现双手肌肉萎缩,无肢体麻木。周围神经传导速度检查显示诱发电位未能引出或波幅显著下降,感觉神经较运动神经改变更明显。视诱发电位提示双眼P100潜伏期均延长,波幅正常。眼底照相提示视神经萎缩,视网膜电图正常。患者母亲7岁时开始出现走路费力,10岁出现视力下降。对先证者进行腓肠神经活体组织检查。对先证者及其母亲进行线粒体融合蛋白2( MFN2)基因测序,100名健康人作为正常对照。结果 腓肠神经病理改变主要为有髓神经纤维显著减少,电镜检查发现个别有髓神经纤维出现洋葱球样结构和再生簇结构,个别神经纤维的轴索内可见线粒体聚集和空泡化。先证者和母亲的MFN2基因第19号外显子存在c.2218T＞C杂合突变,导致MFN2第740位的色氨酸由精氨酸替代(W740R)。100名健康对照没有发现该突变。结论 MFN2基因c.2218T＞C突变导致了遗传性运动感觉性神经病6型,其视力下降多出现在脊神经损害之后,周围神经可以存在髓鞘损害。     

腓骨肌萎缩症2个家系的临床、电生理和基因学研究

为了研究腓骨肌萎缩症(CMT)的临床、电生理以及基因突变的特点,该研究收集2个家系先证者以及发病亲属的临床资料、电生理资料、全血和DNA,进行家系分析及CMT相关基因检测.结果发现家系1为常染色体显性遗传,患者MLPA检测提示PMP22基因的重复扩增.基因测序未发现患者携带CMT其他相关基因的突变.进一步在患者的3个患病的亲属中发现携带PMP22基因的重复扩增,并且未发现其未患病的叔叔携带该突变.家系2为常染色体隐性遗传,先证者携带SH3TC2基因的c.730C＞T p.Q244X和c.432C＞G p.Y144X两个杂合突变.患者的父母,则分别携带上述两个突变.因此,家系1诊断为CMT1A型,家系2诊断为CMT4C型,临床实践中应注意基因和表型的联系.     

TTR Val50Leu突变导致家族性淀粉样多发性神经病的临床和电生理研究

目的分析TTR Val50Leu突变导致家族性淀粉样多发性神经病的临床和电生理特点。方法对一个由TTR Val50Leu突变导致的家族性淀粉样多发性神经病家系进行报道,先证者以足部疼痛为首发症状,2年内逐渐向小腿及上肢进展,并出现自主神经症状。通过对先证者及其家系中相关者进行临床表现、电生理检查及基因检测,分析该病的临床和电生理特点。结果先证者的外祖父、母亲、舅舅、弟弟(其外祖父、母亲、舅舅已故)与其具有相似症状。先证者电生理检查上肢正中神经感觉传导受累,运动正常,尺神经的感觉传导及运动传导均正常,但尺神经F波异常,下肢胫神经和腓总神经的感觉传导及运动传导均未见肯定波形,腓肠神经受累,交感皮肤反应未引出。其弟弟上肢正中神经及尺神经改变同先证者,下肢胫神经运动波幅下降,腓总神经运动正常,交感皮肤反应四肢波幅降低,余同先证者。其女儿上述电生理检查未见异常。基因检测发现三者均在TTR基因exon2存在c.148GT突变,TTR蛋白存在Val50Leu突变。结论 TTR Val50Leu突变导致的家族性淀粉样多发性神经病家系属早发型,以足部疼痛为首发症状,进展迅速,自主神经症状出现较早。电生理符合多发性神经病表现,早期可伴有交感皮肤反应波幅降低。     

HtrA丝氨酸肽酶1基因新突变导致的常染色体隐性遗传性脑动脉病伴皮质下梗死及白质脑病一例

目的 总结1例HtrA丝氨酸肽酶1(HTRA1)基因新突变导致的常染色体隐性遗传性脑动脉病伴皮质下梗死及白质脑病(CARASIL)患者临床特点.方法 患者为34岁女性,下肢肌肉痉挛疼痛16年,腰痛、头痛、脱发5年,右侧轻偏瘫5个月,尿、便潴留1个月.脊椎MRI示颈椎和腰椎退行性变和椎间盘突出.头 MRI示广泛脑白质损害、多发腔隙性梗死灶.患者进行腓肠神经和皮肤活体组织检查.患者及其父母和2个弟弟均进行了HTRA1基因的直接测序,患者进行Notch3基因直接测序,以100名健康者作为对照.结果 光镜下可见小动脉内弹力板不连续和内膜增厚,毛细血管基底膜增厚,电镜下呈现细颗粒样改变.患者HTRA1基因第2号外显子存在c.524T＞A纯合突变,其父母及2个弟弟存在c.524T＞A杂合突变.未发现Notch3基因突变.100名健康对照无此突变.结论 HTRA1基因c.524T＞A新突变导致的CARASIL可以伴随偏头痛和尿、便潴留.     

远端型遗传性运动神经病Ⅴ型一家系

目的 报道1个远端型遗传性运动神经病Ⅴ型(dHMN-Ⅴ)家系的临床、病理和基因改变特点.方法 该家系中连续4代有9例(4例男性,5例女性)在13～40岁之间发病,其中6例出现下肢无力;有2例女性患者仅出现双手肌肉无力和萎缩,其中1例出现锥体束征.先证者为20岁女性,13岁时发现双手肌肉萎缩和无力,15岁后出现下肢无力;肌电图提示神经源性损伤,神经传导速度检查显示运动神经复合肌肉动作电位波幅显著降低,伴随传导速度轻度减慢,感觉神经传导速度和动作电位波幅均正常.对先证者进行腓肠神经活体组织病理检查,并对先证者和其他4例发病者进行血Berardinelli-Seip先天性脂肪营养不良基因2(BSCL2)基因检查.结果 病理检查显示腓肠神经的有髓神经纤维数量轻度减少,伴随个别有髓神经纤维再生簇以及洋葱球样改变.基因检查显示BSCL2基因的第3号外显子存在263A→G杂合突变.结论 临床和基因检查证实该家系为dHMN-Ⅴ,其发病年龄和临床表现在同一家系中存在异质性,可以伴随轻微锥体束征和感觉神经损害.     

腓骨肌萎缩症的临床、病理学及遗传学特点(附1家系报告)

目的:探讨腓骨肌萎缩症(CMT)的临床、病理学及遗传学特点.方法:对1例CMT患者及其家系的临床资料进行回顾性分析.结果:本家系患者主要表现为先天性慢性进行性双下肢远端肌无力和肌肉萎缩,部分伴双上肢受累;腱反射消失,双下肢感觉减退;弓形足.神经电生理检查示周围神经损害,正中神经传导速度＞38m/s.先证者肌肉病理示I型...     

Recurrent central nervous system white matter changes in charcot–Marie–Tooth type X disease

Introduction: X‐linked Charcot–Marie–Tooth (CMT1X) disease is caused by mutations in the GJB1 gene. We describe a young man who presented with recurrent central nervous symptoms and transient white matter changes in the setting of a novel mutation in the GJB1 gene. Methods: Evaluation included clinical examination, neuroimaging, electrophysiological, and molecular genetic studies. Results: Clinical examination on 2 admissions 5 years apart demonstrated hemiparesis with findings of underlying peripheral neuropathy. Electrophysiologic studies revealed a sensorimotor polyneuropathy. MRI studies from both admissions revealed white matter changes, with improvement on an intervening study. Mutation analysis showed a novel mutation (c.98T>A; p.Ile33Asn) in the GJB1 gene. Conclusions: Mutations in GJB1 can result in recurrent central nervous system symptoms with transient white matter signal changes on MRI. In patients presenting with hemiparesis, the presence of signs of a peripheral neuropathy may facilitate identification of CMT1X, and is likely to affect clinical management. Muscle Nerve 49 :451–454, 2014     

X‐linked Charcot‐Marie‐Tooth type 1: stroke‐like presentation of a novel GJB1 mutation

X‐linked Charcot‐Marie‐Tooth type 1 (CMTX1) is the second most common type of CMT and is caused by mutations in the Gap‐Junction Beta‐1 gene (GJB1), encoding connexin 32 which is expressed in Schwann cells as well as in oligodendrocytes. More than 400 GJB1 mutations have been described to date. Many mutation‐carrier males have subclinical central nervous system (CNS) involvement, a few show mild CNS clinical signs, whereas only rarely overt though transient CNS dysfunction occurs. We report a 29‐year‐old man with CMTX1 who, at 16 years, showed short‐lived CNS symptoms with transitory white matter abnormalities on cerebral magnetic resonance imaging (MRI) as first clinical presentation of a novel GJB1 mutation (p.Gln99_His100insGln). He had three consecutive episodes of right hemiparesis, together with sensory loss in the paretic limbs and expressive aphasia, all lasting a few hours, over a 2‐day period, with concurrent white matter hyperintensity on MRI. These “stroke‐like” episodes occurred just after arriving at sea level, after travelling from home at 700 m of altitude. Only a few years later did symptoms of peripheral neuropathy appear. In conclusion, CMTX1 should be included in the differential diagnosis of diseases characterized by transient CNS symptoms and white matter abnormalities on MRI.     

A novel <Emphasis Type="Italic">GJB1</Emphasis> frameshift mutation produces a transient CNS symptom of X-linked Charcot–Marie–Tooth disease

X-linked Charcot–Marie–Tooth disease (CMT1X) is the second most common variant of CMT and is caused by mutations in the GJB1 gene encoding connexin 32. Some CMT1X patients with GJB1 missense mutations have shown transient central nervous system (CNS) symptoms with abnormal brain magnetic resonance imaging (MRI). Herein we report the first case with a novel GJB1 frameshift mutation that associates with a transient CNS symptom. The patient noticed high-arched feet and limited ankle dorsiflexion in early childhood; he transiently developed numbness and paresis of left face and arm, and dysphagia, with abnormal brain MRI. Although the CNS symptoms recovered within several hours without treatment, intravenous immunoglobulin (IVIg) therapy ameliorated progressing symptoms such as those of toe extensor muscles. His mother had been diagnosed with chronic inflammatory demyelinating polyneuropathy (CIDP), and repetitive IVIg treatments had relieved the symptoms. Therefore, inflammation might be involved in the pathophysiology of CMT1X with the GJB1 mutation, while molecular analysis revealed that the mutant GJB1 was more rapidly degraded by the proteasome pathway known as endoplasmic reticulum (ER)-associated degradation.     

Phenotype expression in women with CMT1X

Charcot-Marie-Tooth disease type 1X (CMT1X) is the second most common inherited peripheral neuropathy. Women with CMT1X typically have a less severe phenotype than men, perhaps because of X-inactivation patterns. Our objective was to determine the phenotype of women with CMT1X and whether X-inactivation patterns in white blood cells (WBCs) differ between females with CMT1X and controls. Thirty-one women with CMT1X were evaluated using the CMT neuropathy score (CMTNS) and the CMT symptom score in cross-sectional and longitudinal analyses. Lower scores correspond to less disability. WBCs were analyzed for X-inactivation pattern by androgen receptor X-inactivation assay in 14 patients and 23 controls. The 31 women's mean CMTNS was 8.35. Two-thirds of the cohort had a mild CMTNS (mean 4.85) and one-third had a moderate CMTNS (mean 14.73). Three patients had a CMTNS of 0. The pattern of X-inactivation did not differ between the affected and control groups. Women with CMT1X presented with variable impairment independent of age, type of mutation, or location of mutation. No evidence supported the presence of a gap junction beta-1 (GJB1) mutation affecting the pattern of X-inactivation in blood. Further studies are planned to determine whether X-inactivation is the mechanism for CMT1X females' variable phenotypes.     

Episodic neurological dysfunction in hereditary peripheral neuropathy

Episodic transient neurological symptoms are an important set of problems presenting to a neurologist in his routine practice. Occasionally, detailed clinical history including past and family history supplemented with focused examination can bring out a rare cause for such symptoms. We describe in this report in a young male presenting with episodic focal neurological dysfunction, with family history of similar episodes in mother and brother. Examination showed features of pes cavus and peripheral neuropathy for which patient was asymptomatic. Mother and brother were established cases of hereditary neuropathy. Imaging on multiple occasions showed reversible white matter abnormalities. Clinical suspicion of X-linked Charcot-Marie-Tooth disease type 1 (CMT1X) was confirmed with detection of mutation in Gap Junction B1 (GJB1) gene, which codes for connexin 32 protein (c.425G>A; p.R142Q hemizygous mutation). Though this mutation has been already reported in CMTX patients, it has not been associated with transient neurological dysfunctions. This is probably the first reported case of CMTX patient with transient neurological dysfunction from India, whose family members had similar episodes.     

Exome sequencing reveals mutations in MFN2 and GDAP1 in severe Charcot–Marie–Tooth disease

The aim of our study was to characterize electrophysiologically and explain the genetic cause of severe Charcot–Marie–Tooth (CMT) in a 3.5‐year‐old with asymptomatic parents and a maternal grandfather with a history of mild adult‐onset axonal neuropathy. Severity of neuropathy was assessed by Charcot–Marie–Tooth neuropathy score (CMTNS). Whole‐exome sequencing was performed using an Illumina TruSeq Exome Enrichment Kit on the HiSeq 1500 with results followed up by Sanger sequencing on an ABI Prism 3500XL (Applied Biosystems, Foster City, CA, USA). Paternity was confirmed using a panel of 15 hypervariable markers. Electrophysiological studies demonstrated severe axonal sensory‐motor neuropathy in the proband, mild motor neuropathy in his mother, and mild sensory‐motor neuropathy in his grandfather. CMTNS in the proband, his mother, and grandfather was 21, 1, and 12, respectively. On genetic analysis, the boy was found to carry a heterozygous dominant MFN2 T236M mutation transmitted via the maternal line and a de novo GDAP1 H123R mutation. Our findings emphasize the need to search for more than one causative mutation when significant intrafamilial variability of CMT phenotype occurs and underline the role of whole‐exome sequencing in the diagnosis of compound forms of CMT disease.     

Case report of transient splenium abnormality in Charcot-Marie-Tooth disease]

We report a patient of Charcot-Marie-Tooth disease (CMT) accompanied by transient splenium abnormality in brain MRI. A 34-year-old man suffered from chronic progressive unsteadiness and sensory disturbance of all limbs. Neurological examination showed muscle weakness and atrophy in the distal extremities with pes cavus, mild sensory disturbance of four extremities and generalized decreased reflexes. The nerve conduction study described the presence of sensory-motor polyneuropathy. We could not investigate his GJB1 gene. However, we suspected that he was X-linked CMT (CMTX), because his electrophysiological findings showed intermediate slowing of MCV, and auditory brain-stem response (ABR) demonstrated central conduction slowing. Brain MRI revealed the abnormal high signal intensity in the splenium of the corpus callosum on T2-weighted image. This lesion diminished two months later without any treatment. Recently, there had been reported transient splenium abnormality in CMTX cases, and there were clinical similarities between the cases of these reports and our case. We considered that the pathophysiology of this case was the disruption of gap junction communications expressed between oligodendrocyte and astrocytes induced by connexin 32 (Cx32) mutations. Furthermore, the transient functional disturbance of astrocytes would be another pathophysiologic mechanism of splenium abnormality.     

A novel mutation of gap junction protein β 1 gene in X-linked Charcot-Marie-Tooth disease

Introduction: In this study we report a novel mutation in the gap junction protein beta 1 (GJB1) gene of a Chinese X‐linked Charcot–Marie–Tooth disease (CMTX1) family, which has specific electrophysiological characteristics. Methods: Twenty members in the family were studied by clinical neurological examination and GJB1 gene mutation analysis, and 3 patients were studied electrophysiologically. The proband and his mother also underwent sural nerve biopsy. Results: All patients have the CMT phenotype, except for 2 asymptomatic carriers. Electrophysiological examinations showed non‐uniform slowing of motor conduction velocities and partial motor conduction blocks and temporal dispersion. Sural nerve biopsy confirmed a predominantly demyelinating neuropathy, and an Asn2Lys mutation in the amino‐terminal domain was found in 9 members of this family, but not in 25 normal controls in the family. Conclusions: This family represents a novel mutation in the GJB1 form of CMTX1. The mutation in the amino‐terminus has an impact on the electrophysiological characteristics of the disease. Muscle Nerve, 2011     

Mosaicism for GJB1 mutation causes milder Charcot-Marie-Tooth X1 phenotype in a heterozygous man than in a manifesting heterozygous woman

Charcot-Marie-Tooth (CMT) disease is a heterogeneous disorder of the peripheral nervous system that collectively affects approximately 1 in 2,500 individuals, thus making it the most common inherited neurologic disorder. X-linked inheritance may account for 10–20 % of CMT neuropathy. We report a Czech family with a 30-year-old woman affected by CMT since the age of 10 years, originally as an isolated case. Nerve conduction study (NCS) showed demyelinating neuropathy, and DNA testing revealed a novel heterozygous gap junction beta-1 protein (GJB1) mutation c.784_786delTA. The same mutation, but surprisingly in heterozygous state, was subsequently found in her subjectively healthy father and later also in one of her sisters but not in her two other sisters. NCS showed intermediate type of motor and sensory neuropathy in these two females manifesting heterozygotes and normal results in the other healthy sisters and one brother, all without the c.784_786delTA mutation. The father has a phenotype milder than his daughter and has only subclinical signs of CMT. The index female patient had normal karyotype 46, XX, and normal FISH for centromeric X chromosome. We concluded that the proband’s father is a heterozygote due to the somatic mosaicism for the GJB1 mutation in his leukocytes (detected by DNA sequencing) and also in his germ cells as confirmed by the unexpectedly different genotypes in his four daughters. Quantitative analysis revealed a mutated signal in 25:75 allele proportion of mutated to healthy allele in the mosaic father. This study has important consequences for genetic counseling and prognosis in CMTX1 families.     

NDRG1-linked Charcot-Marie-Tooth disease (CMT4D) with central nervous system involvement

Charcot-Marie-Tooth disease type 4D (CMT4D) is an autosomal recessive demyelinating polyneuropathy, associated with deafness exclusively found in Gypsies and resulting from a homozygous R148X mutation in the N-myc downstream-regulated gene 1 (NDRG1). We report the detailed phenotypic study of a family without Gypsy ancestry, who presented with severe demyelinating polyneuropathy, deafness, subcortical white matter abnormalities on brain magnetic resonance imaging studies, and the R148X mutation in NDRG1. For the first time, central nervous system white matter lesions are demonstrated in CMT4D. This report extends the clinical knowledge of CMT4D and indicates that the role of the R148X mutation in NDRG1 in the central nervous system should be further studied.