肢带型肌营养不良症2A型临床前期两例临床表型及基因突变分析

目的总结肢带型肌营养不良症2A型(LGMD2A型)临床前期的临床表现、实验室检查、影像学检查、神经电生理学检查、基因检测和家系资料等,为LGMD2A型的早期诊断提供临床依据。方法与结果 2例男性患儿,均4岁,幼儿园入学体格检查发现血清肌酸激酶升高(分别为正常参考值上限的25和60倍),运动功能良好,例1伴反复多发性皮疹和背部毛发轻度增多的皮肤损害表现,例2表现为双侧小腿稍肥大坚实,肌电图和肌肉组织活检均提示肌源性损害,双侧大腿肌肉MRI未见明显异常。二代基因测序显示,2例患儿均存在CAPN3基因复合杂合突变:例1存在复合杂合的错义突变[c.2092CT(p.Arg606Ser)]和移码突变[c.712del T(p.Phe239Leufs Ter14)],2个突变位点均未见报道;例2存在复合杂合的错义突变[c.600CG(p.Phe200Leu)和c.619AG(p.Lys207Glu)],c.600CG(p.Phe200Leu)突变位点未见报道。Sanger测序证实二者家系均符合常染色体隐性遗传。2例患儿明确诊断为LGMD2A型,两家系明确诊断为LGMD2A型家系。结论无症状高肌酸激酶血症应考虑LGMD2A型的可能,本研究增加了人群CAPN3基因突变的多样性。     

脂肪酸羟化酶相关性神经变性病四例临床表型及基因突变分析

目的报道4例脂肪酸羟化酶相关性神经变性病患者,并复习相关文献,总结该病临床表型和基因突变特点。方法收集4例脂肪酸羟化酶相关性神经变性病患者临床资料和家系资料,标准酚氯仿法提取患者及其父母基因组DNA并行Sanger测序。结果 4例患者中3例(例2、例3和例4)具有典型脂肪酸羟化酶相关性神经变性病表现,1例(例1)表现为非典型。FA2H基因检测显示,4例患者均存在FA2H基因突变,其中例1为复合杂合突变c.461GA(p.Arg154His)和c.794TG(p.Phe265Cys);例2仅发现1种已报道的杂合突变c.703CT(p.Arg235Cys),进一步对例2及其母进行单核苷酸多态性检测,亦未发现缺失突变;例3为杂合突变c.688GA(p.Glu230Lys)和插入突变c.172_173ins GGGCCAGGAC(p.Ile58Argfs X47);例4为复合杂合突变c.688GA(p.Glu230Lys)、c.968CA(p.Pro323Gln)和c.976GA(p.Gly326Asp),其父为c.688GA(p.Glu230Lys)突变携带者,其母为c.968CA(p.Pro323Gln)和c.976GA(p.Gly326Asp)突变携带者。根据美国医学遗传学和基因组学会标准,例1的FA2H基因杂合突变c.461GA(p.Arg154His)为"可能致病"、c.794TG(p.Phe265Cys)为"可能致病";例2的FA2H基因杂合突变c.703CT(p.Arg235Cys)为"可能致病";例3的FA2H基因杂合突变c.688GA(p.Glu230Lys)为"致病"、插入突变c.172_173ins GGGCCAGGAC(p.Ile58Argfs X47)为"致病";例4的FA2H基因杂合突变c.688GA(p.Glu230Lys)为"致病"、c.968CA(p.Pro323Gln)为"致病"、c.976GA(p.Gly326Asp)为"可能致病"。结论脂肪酸羟化酶相关性神经变性病具有高度临床和遗传异质性,痉挛性截瘫是最主要的临床表现,对于复杂型常染色体隐性遗传性遗传性痉挛性截瘫,尤其合并构音障碍、智力减退、脑白质病变和小脑萎缩等临床特征的患者,应考虑FA2H基因突变导致的脂肪酸羟化酶相关性神经变性病。     

共济失调毛细血管扩张症四例临床表型及基因突变分析

目的报道4例经基因检测明确诊断的共济失调毛细血管扩张症患者,结合文献总结该病临床表型和基因突变特点。方法采集3个共济失调毛细血管扩张症家系共4例患者临床资料,并提取患者及其父母外周静脉血,采用全外显子测序和Sanger测序进行ATM基因突变分析。结果 4例共济失调毛细血管扩张症患者均表现为儿童期发病的进行性进展的小脑共济失调、球结膜和皮肤毛细血管扩张、免疫缺陷导致反复感染,血清甲胎蛋白水平升高,头部MRI显示小脑萎缩。ATM基因检测显示,例1和例2存在已知复合杂合突变c.8287CT(p.Arg2763X)和c.9139CT(p.Arg3047X),均为无义突变;例3存在2种未报道的复合杂合突变,包括无义突变c.8911CT(p.Gln2971X)和缺失突变c.7141_7151del AATGGAAAAAT(p.Asn2381Glufs X18);例4存在纯合突变c.1402_1403del AA(p.Lys468Glufs X18)。结论 4例患者具有典型共济失调毛细血管扩张症临床表现。变异型共济失调毛细血管扩张症患者神经系统受累较轻,头部MRI通常正常,神经系统以外受累少见,明确诊断仍依靠ATM基因检测。     

MTMR13/SBF2基因复合杂合突变致腓骨肌萎缩症4B2型一家系临床表型及基因突变分析

目的探讨腓骨肌萎缩症4B2型(CMT4B2型)的临床表型和分子遗传学特征。方法一家系3例CMT4B2型患儿,采用目标区域捕获测序技术检测MTMR13/SBF2基因突变类型。结果例1(先证者)6年前出现双下肢无力,行走向前跨步,跑步速度较同班同学明显缓慢,随后症状逐渐加重,出现双手大小鱼际肌和骨间肌萎缩,双侧指关节不能伸直,双侧小腿肌萎缩,双侧马蹄内翻足和四肢腱反射减弱。例2(先证者之大弟)2年前出现双下肢无力,行走不稳,跑步和上楼梯较前明显缓慢,步态异常逐渐加重,足跟行走不能,双手大小鱼际肌萎缩,双侧小腿轻度肌萎缩,四肢腱反射减弱。例3(先证者之二弟)足跟行走困难,双手大小鱼际肌轻度肌萎缩,四肢腱反射减弱。基因检测显示,例1存在MTMR13/SBF2基因c.230GA(p.Gln77Arg)和c.1537CT(p.Gln513~*)复合杂合突变,其父携带c.230GA(p.Gln77Arg)杂合突变,其母携带c.1537CT(p.Gln513~*)杂合突变,例2和例3均存在与先证者相同的c.230GA(p.Gln77Arg)和c.1537CT(p.Gln513~*)复合杂合突变。3例患儿诊断明确为CMT4B2型,该家系明确诊断为CMT4B2型家系。予甲钴胺对症治疗,先证者马蹄内翻足明显,予石膏固定疗法予以纠正。结论 CMT4B2型是罕见且严重的进展型腓骨肌萎缩症,目前尚无有效治疗方法,对患者进行及时的基因检测以明确诊断,同时对患病家系积极开展遗传咨询,对于有生育要求的致病基因携带者还应结合产前基因诊断以避免患病胎儿的出生。对于家系中携带致病基因尚未出现临床症状或处于疾病早期的患者,应密切随访,采取积极治疗以尽可能延迟发病时间或指导患者进行正确的康复训练以预防弓形足、脊柱侧弯等畸形,从而提高生活质量。     

常染色体显性遗传腓骨肌萎缩症一家系致病基因分析

目的 定位分析一常染色体显性遗传腓骨肌萎缩症家系的致病基因.方法 依据家系图、临床表现、神经肌肉电生理学及实验室检查结果,明确诊断一常染色体显性遗传腓骨肌萎缩症家系.采用16个基因位点的37个短串联重复序列(STR)标记方法进行连锁分析,以覆盖目前已经发现的20种常染色体显性遗传腓骨肌萎缩症亚型的16个致病基因位点.结果 所选择的37个STR标记均发生扩增反应,每一基因位点均呈现多态性.受检腓骨肌萎缩症家系呈常染色体显性遗传,其中3例患者在17p11.2-p12、1q22、16p12.3-p13.1、10q21.1、1p36.2、3q21、12q23、7p15、8p21、7q11-q21、12q12-q13、8q13-q21、12q24.3、10q24、19p12-p13及1p34-p35共16个基因位点的单倍体型均不存在等位基因共享,且家系所有成员致病基因均与16个已知常染色体显性遗传腓骨肌萎缩症致病基因位点不连锁.结论 研究过程中每一基因位点所用STR标记为2～3个,基本可以排除染色体互换,常染色体显性遗传腓骨肌萎缩症家系诊断依据充分;根据欧洲神经肌肉病中心制汀的确诊标准,可排除为已知类型的常染色体显性遗传腓骨肌萎缩症家系.推测为一新型腓骨肌萎缩症致病基因所引起的常染色体显性遗传腓骨肌萎缩症家系.     

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。     

CRPPA基因变异导致肢带型肌营养不良症1例

报告1例CRPPA基因变异所致常染色体隐性遗传性肢带型肌营养不良症患者，总结CRPPA基因相关肌病的临床特点和致病变异谱。患者主要临床表现为双下肢无力7年，进行性加重。血清肌酸激酶水平轻度增高。肌电图提示肌源性损害。肌肉MRI表现为双侧大腿、小腿多发肌群信号异常。骨骼肌活检组织电镜下可见肌细胞胞浆内肌浆网轻度扩张，小脂滴轻度增多，可见少量萎缩肌细胞。基因检测提示携带CRPPA基因c.1114＿1116delGTT (p.V372del)纯合变异。患者父母携带该位点杂合变异。根据ACMG指南将该变异分类为致病性变异。患者明确诊断为肌营养不良-抗肌萎缩相关糖蛋白病C7型。本文拓展了CRPPA基因和抗肌萎缩相关糖蛋白病的遗传变异谱和临床表型谱。     

NPC1基因复合杂合突变致尼曼-匹克病C型一家系

目的报道NPC1基因新发复合杂合突变致尼曼-匹克病C型一家系的临床及遗传学特点, 提高临床医师对该病的认识水平。方法对云南省昆明医科大学第一附属医院神经内科2020年收治的1个非近亲结婚家系中的2例患者进行详细的神经科体格检查, 提取外周血DNA, 应用二代测序技术对患者进行全外显子测序, 结合Sanger测序对患者家系进行一代验证, 应用软件对突变位点进行分析。结果该家系呈常染色体隐性遗传, 2例患者的发病年龄不同, 先证者9岁起病, 主要表现为:构音不良、吞咽困难、认知障碍、共济失调、双侧锥体束损害、垂直核上凝视麻痹和脾脏肿大。先证者弟弟临床表型与患者相似, 但比患者更为严重, 发病年龄更早, 婴幼儿期发病, 伴有严重的精神运动发育迟缓。全外显子组测序结果显示, 两兄弟均携带NPC1基因的两种罕见变异:c.352₃53del, p.Gln119ValfsTer8和c.593A>G, p.Asn198Ser。Sanger测序验证结果提示复合杂合突变分别来源于先证者的父母。根据美国医学遗传学与基因组学学会指南, 上述变异评级分别为致病和疑似致病变异。该家系患...     

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.     

DMD基因点突变致Becker型肌营养不良症临床研究

研究背景DMD基因点突变,主要是无义突变,可以引起基因编码提前终止,使产生的目的蛋白不稳定而降解,导致临床症状较重的Duchenne型肌营养不良症,而在实际工作中可见临床表型为症状较轻的Becker型肌营养不良症的DMD点突变患者。本研究旨在探讨DMD基因点突变导致Becker型肌营养不良症的发病机制,以加深对Becker型肌营养不良症基因突变类型的认识。方法共11例临床和肌肉活检明确诊断、多重连接依赖性探针扩增(MLPA)显示DMD基因外显子非缺失或重复突变的Becker型肌营养不良症患者,高通量第2代DNA测序法检测DMD基因外显子突变类型。结果11例Becker型肌营养不良症患者携带10种突变类型,无突变热点;6例携带无义突变[c.5002GT,p.(Glu1668X);c.1615CT,p.(Arg539X);c.7105GT,p.(Glu2369X);c.5287CT,p.(Arg1763X);c.9284TG,p.(Leu3095X)];1例携带错义突变[c.5234GA,p.(Arg1745His)];2例携带框移突变(c.10231dup T,c.10491del C);2例携带剪切位点突变(c.4518+3AT,c.649+2TC)。结论 DMD基因点突变可以引起临床症状较轻的Becker型肌营养不良症,当MLPA技术显示DMD基因为非缺失和重复突变时,切勿漏诊Becker型肌营养不良症,研究其发生机制对基因治疗Duchenne型肌营养不良症有重要借鉴意义。     

Two recessive intermediate Charcot-Marie-Tooth patients with GDAP1 mutations

Various phenotypes have been reported in Charcot-Marie-Tooth (CMT) disease carrying mutations in the ganglioside-induced differentiation-associated protein 1 (GDAP1) gene. Here, we report two recessive intermediate Charcot-Marie-Tooth (RI-CMT) patients with GDAP1 missense mutations: a His256Arg homozygous mutation (c.767A>G + c.767A>G) and compound mutations of heterozygous Pro111His (c.332C>A) and Val219Gly (c.656T>G). The Pro111His and Val219Gly are unreported mutations, but the His256Arg was previously reported. In both patients, histopathological findings showed well-documented features of mixed demyelinating and axonal neuropathies, and nerve conduction velocities fall in the intermediate range. In addition, the patterns of fatty substitutions in leg magnetic resonance imaging (MRI) were different by the mutation sites within the same GDAP1 gene.     

Novel mutations in the GDAP1 gene in patients affected with early-onset axonal Charcot-Marie-Tooth type 4A

We report a detailed study of eight patients from four Italian families presenting with autosomal recessive axonal Charcot-Marie-Tooth disease (AR-CMT2), characterized by early-onset and progressive severe weakness of all limbs. Vocal cord paresis was present in two cases. Sural nerve biopsy performed in three patients showed a severe neuropathy characterized by a predominant axonal involvement. Five novel mutations (p.Gln99stop, p.Gln122Lys, p.Arg125stop, p.Val219Asp, p.Asn297Lys) and one previously reported mutation (p.Leu239Phe) were identified in GDAP1 gene. GDAP1 mutations should be considered both in recessive and sporadic cases of early-onset axonal CMT.     

A novel GDAP1 mutation 439delA is associated with autosomal recessive CMT disease

BACKGROUND: Charcot-Marie-Tooth (CMT) disease is the most common form of inherited motor and sensory neuropathy. Based on neurophysiological and neuropathological criteria CMT has been sub-classified into two main types: demyelinating and axonal. Furthermore, it is genetically heterogeneous with autosomal dominant, autosomal recessive (AR) and X-linked modes of inheritance. Thus far, seven genes have been identified in association with the demyelinating AR-CMT disease. We hereby report our clinical and molecular genetic findings in a consanguineous family with AR-CMT. METHODS: Two young sisters with AR-CMT and other non-affected family members were clinically and electrophysiologically evaluated and then molecular genetic investigation was carried out in order to identify the pathogenic mutation. RESULTS: Following an initial indication for linkage of the family to the CMT4A locus on chromosome 8, we sequenced the Ganglioside-induced differentiation-associated protein 1 (GDAP1) gene and identified a single nucleotide deletion in exon 3 that is associated with AR-CMT in the family. CONCLUSIONS: We identified a novel GDAP1 439delA mutation that is associated with AR-CMT in a consanguineous family of Iranian descent with two affected young girls and a history in other members of the family.     

Two novel mutations in the GDAP1 and PRX genes in early onset Charcot-Marie-Tooth syndrome

Autosomal recessive Charcot-Marie-Tooth syndrome (AR-CMT) is often characterised by an infantile disease onset and a severe phenotype. Mutations in the ganglioside-induced differentiation-associated protein 1 (GDAP1) gene are thought to be a common cause of AR-CMT. Mutations in the periaxin (PRX) gene are rare. They are associated with severe demyelination of the peripheral nerves and sometimes lead to prominent sensory disturbances. To evaluate the frequency of GDAP1 and PRX mutations in early onset CMT, we examined seven AR-CMT families and 12 sporadic CMT patients, all presenting with progressive distal muscle weakness and wasting. In one family also prominent sensory abnormalities and sensory ataxia were apparent from early childhood. In three families we detected four GDAP1 mutations (L58LfsX4, R191X, L239F and P153L), one of which is novel and is predicted to cause a loss of protein function. In one additional family with prominent sensory abnormalities a novel homozygous PRX mutation was found (A700PfsX17). No mutations were identified in 12 sporadic cases. This study suggests that mutations in the GDAP1 gene are a common cause of early-onset AR-CMT. In patients with early-onset demyelinating AR-CMT and severe sensory loss PRX is one of the genes to be tested.     

A novel autosomal dominant GDAP1 mutation in an Italian CMT2 family

We report the clinical, electrophysiological, and skin biopsy findings of an Italian Charcot-Marie-Tooth disease type 2 (CMT2) family with a novel heterozygous GDAP1 mutation. We observed a marked intra-familial phenotypic variability, in age at onset and disease severity which ranged from a typical CMT phenotype to an asymptomatic status. Electrophysiological study, consistent with an axonal sensory-motor neuropathy, confirmed a different degree of severity and disclosed minimal electrophysiological abnormalities also in the asymptomatic subjects. Skin biopsy findings showed a variable loss of large and small somatic nerve fibers. Molecular analysis identified a novel heterozygous missense mutation (Arg120Gly) in the GDAP1 gene which co-segregated with the disease within the pedigree. In conclusion, our findings confirm that the GDAP1 autosomal dominant mutations underlie a pronounced phenotypic variability, mimicking the effects of reduced penetrance. Notably, electrophysiological study in this family allowed to reveal hidden positive family history and assess a dominant inheritance pattern, revealing subclinical neuropathy in asymptomatic mutation carriers.     

Charcot-Marie-Tooth disorders with an autosomal recessive mode of inheritance

In recent years, 13 loci and 10 genes have been identified in Charcot-Marie-Tooth disorders with a recessive mode of inheritance (AR-CMT). Accordingly, the entity of AR-CMT has been divided into subgroups on the basis of genetic linkage. Mutations in the MTMR2, MTMR13, GDAP1, PRX, CTDPI, KIAA1985 and NDRG1 genes have been shown to be associated with specific CMT phenotypes. In AR-CMT disorders associated with mutations in the LMNA and MED25 genes the number of patients is still too low to achieve reliable phenotype-genotype correlations. In the present review, we summarize molecular, electrophysiological, neuropathological and clinical aspects of AR-CMT disorders.     

A novel compound heterozygous mutation in the POMK gene causing limb-girdle muscular dystrophy-dystroglycanopathy in a sib pair

We describe two Finnish siblings in whom an incidentally detected elevated creatine kinase activity eventually led to a diagnosis of limb-girdle muscular dystrophy-dystroglycanopathy (Type C12; MDDGC12). When diagnosed at age 10 and 13 years, they were mildly affected with a slow or non-progressive disease course. The main symptoms comprised infrequent hip cramps triggered by flexion, neck cramps triggered by yawning, transient growing pains, calf hypertrophy and mild proximal muscle weakness. Their cognitive and motor developments were unremarkable and they were physically active. Whole-exome sequencing revealed compound heterozygous mutations, both of which were novel, in the protein O-mannosyl kinase (POMK) gene in both siblings; a missense mutation, p.Pro322Leu (c.965C > T), and a nonsense mutation, p.Arg46Ter (c.136C > T). The results were confirmed by Sanger sequencing, showing that the parents were heterozygous carriers of one mutation each. This report adds to the literature by providing phenotype and genotype data on this ultra-rare POMK-related dystroglycanopathy.     

A French family with Charcot-Marie-Tooth disease related to simultaneous heterozygous MFN2 and GDAP1 mutations

Either dominantly inherited mutations in MFN2 encoding mitofusin 2 or GDAP1 encoding ganglioside-induced differentiation associated protein 1 may be associated with mild neuropathy. The proband, a 41-year-old woman, and her daughter present a severe axonal form of Charcot-Marie-Tooth (CMT) disease. Both are heterozygous for the well-described mild variant p.R120W in GDAP1, which was transmitted by the pauci symptomatic proband's mother. Given that they had an early onset in the first decade and delayed walking acquisition, the other genes implicated in axonal forms of CMT disease were analyzed. A second mutation truncating MFN2 (p.Val160fsX26) was found in the proband and her daughter. This mutation was transmitted by the proband's father who has normal neurological examination. The proband underwent two nerve biopsies which showed an axonal degeneration, myelin modifications, and intra-axonal mitochondria with distorted cristae. Such abnormal mitochondria have been reported in cases with autosomal dominant MFN2 mutations and in one patient with an autosomal recessive GDAP1 mutation. Our two cases show that heterozygous truncation of MFN2, which is silent at least until the sixth decade, when combined with the mild p.R120W GDAP1 variant, leads to a severe neuropathy. This supports the emerging hypothesis of cumulative effects of MFN2 and GDAP1 mutation.