眼咽型肌营养不良汉族六家系的临床和遗传学特点

目的 初步总结我国汉族眼咽型肌营养不良(OPMD)患者的临床和多腺苷酸结合蛋白核1(PABPN1)基因改变特点.方法 6个OPMD家系共28例患者,男性13例,女性15例,发病年龄32～70岁,平均发病年龄49.7岁.在可确定首发症状的患者中,以吞咽困难或构音障碍首发的13例、眼睑下垂首发的4例、双下肢无力首发的1例.经过3～20年均出现眼睑下垂、吞咽困难和构音障碍,其中7例出现四肢近端无力.对6例先证者做肌肉活体组织检查,标本进行常规组织病理和电镜检查.对6个家系的先证者以及部分家庭成员进行PABPN1基因检查,并对6例先证者进行单体型分析.结果 6例先证者的肌肉活体组织检查均发现肌纤维直径轻度变异加大伴随肌纤维内镶边空泡形成,4例患者经电镜检查发现OPMD典型的核内栅栏样丝状包涵体.3个家系的PABPN1基因型为(GCG)9,另外3个家系的基因型分别为(GCG)6(GCA)1(GCG)3、(GCG)10和(GCG)8.2个携带(GCG)9突变的家系存在rs2239579(C)-(GCG)9-SNP2622(C)的单倍体型.结论 吞咽异常和眼睑下垂均是我国汉族OPMD患者的首发症状.肌纤维出现镶边空泡以及核内包涵体是我国患者的常见病理改变.PABPN1基因的(GCG)异常扩增和(GCA)插入突变均出现在我国患者,起源具有多源性.携带(GCG)9突变的部分家系可能来自共同祖先.     

结蛋白基因S12F新突变导致的结蛋白病一家系

目的 报道1个结蛋白基因新突变导致的结蛋白病家系,介绍其临床和病理改变特点.方法 1个常染色体显性遗传家系内共有8例患者,男7例,女1例.发病年龄20～50岁.其中7例有心脏损害,3例有肢体近端无力,1例伴慢性腹泻.先证者和其兄行左肱二头肌活体组织检查,进行组织学、酶组织化学、电镜观察及抗结蛋白等免疫组织化学染色.先证者和3例患者、5名无症状家系成员及50名健康人行结蛋白基因测序.结果 先证者的骨骼肌出现肌纤维直径变异加大伴结缔组织增生,少数肌纤维出现嗜酸性改变伴镶边空泡,其兄的骨骼肌仅在许多肌纤维内出现小圆状嗜酸性包涵体.肌纤维内包涵体和肌纤维膜下结蛋白阳性.电镜显示先证者肌纤维内颗粒物质沉积.4例患者存在结蛋白基因S12F突变,无症状家系成员和健康对照无此突变.结论 结蛋白S12F新突变导致的结蛋白病多出现在男性,以心脏病多见.病理改变在家系不同患者之间存在差异.     

眼咽型肌营养不良一家系临床与分子遗传学研究

目的探讨一考虑诊断眼咽型肌营养不良(oculopharyngeal muscular dystrophy,0PMD)家系的临床及分子生物学特点。方法收集该家系成员的临床资料,并经包括先证者在内的16位家族成员同意,收集其血样进行聚合酶链反应(PCR)基因验证分析。结果该家系成员男性患者起病以眼睑下垂为首发症状,而后开始逐渐出现以发音及吞咽困难为表现的咽部肌群和肢体乏力为表现的四肢近端肌群受累,而女性患者则往往以吞咽困难为首发表现。参与基因检测的家族成员中共发现10位存在多聚腺苷酸结合蛋白核l(PABPN1)基因的(GCG)6重复异常拷贝为(GCG)10,从而导致了丙氨酸的扩增。结论基因诊断及产前诊断是确诊及预防眼咽型肌营养不良的关键,眼睑下垂可能为携带(GCG)10突变男性OPMD患者的首发症状。     

眼咽型远端型肌病二家系的临床、病理及分子学特点

目的 探讨2个眼咽型远端型肌病(OPDM)家系的临床、病理及分子生物学特点.方法 对2个家系的先证者行血清肌酶、肌电图、肌肉活体组织检查、肌肉酶组织染色及电镜分析,并于复诊时提取其静脉血DNA样本,进一步行编码多聚腺苷酸结合蛋白核1(PABPN1)、GNE基因突变分析.结果 家系1为同代3兄弟发病,家系2为2代4人发病.起病以发音困难伴双下肢无力居多；以发音及吞咽困难为表现的咽部肌群受累较突出.肌肉超微结构电镜分析未见到眼咽型肌营养不良样核内包涵体,2家系先证者PABPN1基因GCN重复拷贝数均为正常(10次,GCG6GCA3GCG1),且GNE基因2～12号外显子均未发现突变.结论 2个OPDM家系起病年龄、形式与日本患者类似,但肌肉受累方式有所不同.家系1为中国首个常染色体隐性遗传OPDM家系.本研究结果证实OPDM是一个表型、病理、遗传学独立的肌病实体.     

以胞质体-球形体为主要病理改变的肌原纤维肌病一家系

目的 报道1个以胞质体和球形体为主要病理改变的肌原纤维肌病家系,分析其临床、病理和基因特点.方法 家系中连续5代10例均在35～40岁出现进行性下肢无力,其中6例出现心肺损害症状,4例出现腹泻.对先证者肌肉活体组织检查标本行组织学、酶组织化学、免疫组织化学(抗tau蛋白、结蛋白、泛素、dysferlin以及dystrophin-C'、N'和R抗体)染色及电镜检查.对肌缩蛋白(MYOT)、α-B晶体蛋白链(CRYAB)、结蛋白、z带选择性接合PDZ蛋白(LDB3)、核纤层蛋白A/C(LMNA)、含硒蛋白N1(SEPN1)基因的外显子以及丝蛋白C(FLNC)基因的第48号外显子进行分析.结果 病理检查显示肌纤维内存在大量胞质体和球形体,伴随结蛋白、tau蛋白、泛素、dysferlin和dystrophin-C'、R蛋白阳性表达.电镜显示包涵体内含致密颗粒样物,其周围为放射样分布的细丝.没有发现上述7种基因外显子序列异常.结论 肌原纤维肌病具有多系统损害特点;肌纤维内存在的胞质体和球形体含有多种微管和膜相关蛋白;该病可能存在未知基因突变.     

眼面咽喉肌受累的一个家系临床及其相关基因的初步研究

目的分析呈常染色体显性遗传，核心症状为眼外肌、面肌、咽喉肌肉瘫痪的一个家系，探讨其分类和病因。方法调查包括先证者在内的5例患者以及该家系中另外26名成员，收集其临床资料，进行电生理、肌肉病理检查，收集血样用PCR法进行基因验证。结果5例接受调查的患者经查体发现：眼睑下垂（5／5），眼外肌麻痹（5／5），面瘫（5／5），吞咽困难、声音嘶哑、咽反射迟钝（5／5），舌肌萎缩（3／5），颞肌萎缩（4／5），咬肌萎缩（4／5），近端肢体无力（3／5），肢体近端肌肉萎缩（4／5），远端肢体无力（3／5），肢体远端肌肉萎缩（4／5）。与眼咽型肌营养不良（OPMD）等疾病进行比较，电生理上确定病灶的性质为肌源性损害，肌肉病理为肌肉萎缩，但没有代谢性病变的表现，因此从电生理和肌肉病理两方支持肌营养不良的诊断。患者和表现健康的成员的PABPN1基因不存在（GCG）。（GCA），GCG的突变。结论该家系临床表现类似OPMD而不同于其他已知疾病，但是基因背景又完全不同于OPMD，可能属于肌营养不良的一种新亚型。     

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.     

常染色体显性遗传性微管聚集性肌病存在SCN4A基因突变(附1家系报告)

目的 探讨显性遗传性微管聚集性肌病的临床、骨骼肌病理和基因改变特点.方法 对显性遗传性微管聚集性肌病1家系进行分析研究,先证者为17岁男性,1岁开始出现发作性面肌、咀嚼肌和四肢肌无力,以及寒冷或活动诱发的肌肉僵硬,发作间期持续性肢体乏力.家族中连续4代10例出现类似临床表现.对先证者及其母亲进行肌肉活检.对母子及家族中无症状者行SCN4A基因序列检测.结果 在先证者和其母亲的Ⅱ型肌纤维肌纤维内均发现异常沉积物,分别占所有肌纤维的10%和3%.免疫组织化学染色见病变肌纤维内tau、dysferlin和泛素阳性表达.电镜检查显示沉积物为大量聚集的微管结构.基因测序发现母子两人的SCN 4A基因第13号外显子存在T704M突变.结论 病理检查证实显性遗传性微管聚集性肌病,该病和SCN4A基因突变有关,出现副肌强直性周期性瘫痪的临床表型.     

眼咽型肌营养不良病理及分子遗传学研究

目的研究眼咽肌营养不良(ocu lopharyngeal muscu lar dystrophy,OPMD)的遗传学和病理形态学表现。方法应用透射电镜技术对6例患者提上睑肌进行超微结构观察和分析,并采用聚合酶链反应(PCR)产物直接测序法对来自3个家系的OPMD患者11例及其亲属共27名外周血进行检测。结果4例患者眼肌活检标本于电镜下可观察到特异性核内包涵体(intranuc lear inc lusions,INIs),在细胞核内出现率分别为18%、20%、34%及40%。而9例患者基因中存在(GCG)6重复序列拷贝数异常(GCG)8、(GCG)10,亲属中未发病者均未见重复序列的异常扩增。结论OPMD患者受累眼肌活组织检查于电镜下可见INIs,并且INIs出现比率与异常扩增数目成正比。OPMD患者存在(GCG)6重复序列的异常扩增,并且发病年龄与异常扩增数目成反比。     

Progress in understanding the pathogenesis of oculopharyngeal muscular dystrophy

Oculopharyngeal muscular dystrophy (OPMD) is an adult-onset disorder characterized by progressive eyelid drooping (ptosis), swallowing difficulties (dysphagia), and proximal limb weakness. The autosomal dominant form of this disease is caused by expansions of a (GCG)6 repeat to (GCG)8-13 in the PABPN1 gene. These mutations lead to the expansion of a polyalanine stretch from 10 to 12-17 alanines in the N-terminal domain of PABPN1. Mutated PABPN1 (mPABPN1) induces the formation of muscle intranuclear inclusions that are thought to be the hallmark of this disease. In this review, we discuss: 1) OPMD genetics and PABPN I function studies; 2) diseases caused by polyalanine expansions and cellular polyalanine toxicity; 3) mPABPN1-induced intranuclear inclusion toxicity; 4) role of oligomerization of mPABPNI in the formation and toxicity of OPMD intranuclear inclusions and; 5) recruitment of subcellular components to the OPMD inclusions. We present a potential molecular mechanism for OPMD pathogenesis that accounts for these observations.     

Oculopharyngeal muscular dystrophy with PABPN1 mutation in a Chinese Malaysian woman

Oculopharyngeal muscular dystrophy (OPMD) is an autosomal dominant disorder of middle age presenting as progressive dysphagia and eyelid ptosis, due to short expansions of the GCG trinucleotide repeat (from GCG6 to GCG8-13) in the polyadenylate binding-protein nuclear 1 (PABPN1) gene. OPMD is rarely seen in Asians and morphologically and/or genetically confirmed cases have been reported in Japanese kindreds only. We report a 64 year old Chinese-Malaysian woman who presented with progressive dysphagia and bilateral ptosis for about 6 years. Her mother and elder brother (both deceased) were believed to be affected. Muscle histopathology revealed angulated fibres with rimmed vacuoles. Genetic analysis showed repeat expansion in one allele to (GCG)9 while normal in the other (GCG)6. This is the first non-Japanese Asian family with genetically confirmed OPMD.     

HnRNP A1 and A/B interaction with PABPN1 in oculopharyngeal muscular dystrophy

BACKGROUND: Oculopharyngeal muscular dystrophy (OPMD) is an adult-onset disorder characterized by progressive ptosis, dysphagia and proximal limb weakness. The autosomal dominant form of this disease is caused by short expansions of a (GCG)6 repeat to (GCG) in the PABPN1 gene. The mutations lead to the expansion of a polyalanine stretch from 10 to 12-17 alanines in the N-terminus of PABPN1. The mutated PABPN1 (mPABPN1) induces the formation of intranuclear filamentous inclusions that sequester poly(A) RNA and are associated with cell death. METHODS: Human fetal brain cDNA library was used to look for PABPNI binding proteins using yeast two-hybrid screen. The protein interaction was confirmed by GST pull-down and co-immunoprecipitation assays. Oculopharyngeal muscular dystrophy cellular model and OPMD patient muscle tissue were used to check whether the PABPN1 binding proteins were involved in the formation of OPMD intranuclear inclusions. RESULTS: We identify two PABPNI interacting proteins, hnRNP A1 and hnRNP A/B. When co-expressed with mPABPN1 in COS-7 cells, predominantly nuclear protein hnRNP A1 and A/B co-localize with mPABPN1 in the insoluble intranuclear aggregates. Patient studies showed that hnRNP A1 is sequestered in OPMD nuclear inclusions. CONCLUSIONS: The hnRNP proteins are involved in mRNA processing and mRNA nucleocytoplasmic export, sequestering of hnRNPs in OPMD intranuclear aggregates supports the view that OPMD intranuclear inclusions are "poly(A) RNA traps", which would interfere with RNA export, and cause muscle cell death.     

A late-onset case of oculopharyngeal muscular dystrophy carrying a (GCG)8 repeat expansion in the PAPBN1 gene]

We report a sporadic case of a female patient with oculopharyngeal muscular dystrophy (OPMD). Her father died at age 86 and mother at age 74. There was no familial occurrence of the disease. The patient initially developed a nasal voice at age 66. Neurological examinations on admission at age 72 revealed bilateral ptosis, a limitation of ocular movement without diplopia, dysphagia, and proximal muscle weakness. Serum creatine kinase level was slightly increased. Biopsied muscle specimens showed variation in fiber size as well as the occasional presence of rimmed vacuoles. On the basis of these clinical and laboratory findings, we suspected a diagnosis of OPMD, although a family history was absent. To confirm the diagnosis of OPMD, we performed a gene analysis for poly A binding protein, nuclear 1 (PABPN1; PABP2), which revealed a mild expansion of GCG repeat (8 repeats) as a heterozygous state. Clinical features of the patient were consistent with those in a previous literature reporting that patients carrying (GCG)8 repeat as a heterozygous state show a relatively late onset and a mild phenotype. The case of this patient emphasizes the importance of the PABPN1 gene analysis for patients showing muscular weakness involving oculopharyngeal and proximal limb muscles even when a familial occurrence of the disease is not apparent.     

Oculopharyngeal muscular dystrophy

Autosomal dominant oculopharyngeal muscular dystrophy (OPMD) is an adult-onset disease with worldwide distribution. It usually presents in the fifth or sixth decades with progressive dysphagia, eyelid ptosis, and proximal limb weakness. Unique intranuclear filament inclusions in skeletal muscle fibers are its morphological hallmark. Surgical correction of the ptosis and cricopharyngeal myotomy are the only therapies available. Autosomal dominant OPMD is caused by short (GCG)8-13 riplet-repeat expansions in the polyadenylation binding protein 2 (PABP2) gene, which is localized in chromosome 14q11. Autosomal recessive OPMD is caused by a double dose of a (GCG)7 PABP2 allele. The GCG expansions cause lengthening of a predicted polyalanine tract in the protein. The expanded polyalanine domains may cause polyalanine nuclear toxicity by accumulating as nondegradable nuclear filaments.     

Identification of a novel mutation in a Korean patient with oculopharyngeal muscular dystrophy.

Oculopharyngeal muscular dystrophy (OPMD) is a late-onset muscle disorder characterized by progressive dysphagia and bilateral ptosis. Mutations in the polyadenylate binding protein nuclear 1 (PABPN1) gene have been found to cause OPMD. The typical mutation is a stable trinucleotide repeat expansion in the first exon of the PABPN1 gene, in which (GCG)(6) is the normal repeat length. We investigated a Korean patient with OPMD and identified a novel mutation: a heterozygous insertion of a 9-bp sequence [(GCG)(GCA)(GCA); c.27_28insGCGGCAGCA] instead of the (GCG) repeat expansion, resulting in an in-frame insertion of three alanines (p.A10insAAA). To the best of our knowledge, this is the first report of a genetically confirmed case of OPMD in Korea.     

Transgenic expression of an expanded (GCG)13 repeat PABPN1 leads to weakness and coordination defects in mice

Oculopharyngeal muscular dystrophy (OPMD) is a late-onset disorder caused by a (GCG)n trinucleotide repeat expansion in the poly(A) binding protein nuclear-1 (PABPN1) gene, which in turn leads to an expanded polyalanine tract in the protein. We generated transgenic mice expressing either the wild type or the expanded form of human PABPN1, and transgenic animals with the expanded form showed clear signs of abnormal limb clasping, muscle weakness, coordination deficits, and peripheral nerves alterations. Analysis of mitotic and postmitotic tissues in those transgenic animals revealed ubiquitinated PABPN1-positive intranuclear inclusions (INIs) in neuronal cells. This latter observation led us to test and confirm the presence of similar INIs in postmortem brain sections from an OPMD patient. Our results indicate that expanded PABPN1, presumably via the toxic effects of its polyalanine tract, can lead to inclusion formation and neurodegeneration in both the mouse and the human.     

Variability of the recessive oculopharyngeal muscular dystrophy phenotype

Oculopharyngeal muscular dystrophy (OPMD) is usually transmitted as an autosomal-dominant trait and characterized by an expansion from 6 to 8 or more GCG/GCA repeats in the poly-(A) binding protein nuclear 1 (PABPN1) gene on chromosome 14q11. Autosomal-recessive OPMD with a homozygous (GCG)7 expansion of PABPN1 has only been described in two Canadian patients, who showed a comparably mild phenotype, suggesting that it is less severe than the dominant form. We clinically and genetically characterized the first two reported cases of autosomal-recessive OPMD in Europe. Remarkably, both patients revealed severe and diverse phenotypes, with an unusual onset and atypical clinical course in one patient. Former studies found a 1%-2% frequency of the (GCG)7 allele, which theoretically produces an incidence of 1:10,000 of autosomal-recessive OPMD in the general population. We conclude that the apparent rarity of the autosomal-recessive form of OPMD may be due to the fact that genetic testing is generally administered only to patients with typical clinical features or a positive family history.