肢带型肌营养不良症2D型一家系临床表型及基因突变分析

目的总结肢带型肌营养不良症2D型(LGMD2D型)临床表型和基因突变特点。方法报道一家系2例女性LGMD2D型患儿临床表现、肌电图、肌肉MRI、肌肉病理学和基因检测结果,并结合相关文献进行分析。结果先证者及其妹均于3岁发病,以进行性四肢近端无力为主要临床表现;血清肌酸激酶水平显著升高;肌电图呈肌源性损害;肌肉MRI显示部分肌肉萎缩、脂肪化或纤维水肿;其妹肌肉病理学显示局灶性骨骼肌坏死、再生,部分横纹肌消失,肌纤维大小不等。基因检测显示,先证者及其妹存在相同基因突变,即SGCA基因第3外显子移码突变c.262del T(p.Phe88SerfsX123)和第5外显子错义突变c.409GA(p.Glu137Lys),其母为SGCA基因c.409GA(p.Glu137Lys)突变携带者,其中,c.409GA(p.Glu137Lys)为已知突变,c.262del T(p.Phe88SerfxX123)为新发突变。结论对于临床类似Duchenne型肌营养不良症的女性患者,排除DMD基因携带者后,还应行家系分析和肢带型肌营养不良症相关基因检测,以明确具体亚型。     

DNAJB6基因突变致显性遗传性肌病一家系并文献复习

目的总结常染色体显性遗传性DNAJB6基因突变所致肌病的临床表型和基因突变特点。方法回顾分析一家系2例DNAJB6基因突变所致肌病患者的临床表现、实验室、肌肉影像学、神经电生理学、肌肉病理学和基因检测结果,并进行文献复习。结果先证者主要表现为四肢远近端肌无力,下肢重于上肢、近端重于远端,其父呈姿势异常,上楼需扶持。二者血清肌酸激酶水平正常,MRI表现为不同程度肌肉脂肪化,组织病理学可见肌营养不良样改变,部分肌纤维内镶边空泡形成,核内移增多或个别肌纤维再生。基因检测提示先证者及其父均携带DNAJB6基因c.161A>C(p.Glu54Ala)杂合突变,为中国大陆首次报道,分别为肢带型肌营养不良症D1型(LGMD?D1型)和远端型肌病型,该家系明确为常染色体显性遗传性DNAJB6基因突变所致肌病家系。结合文献提示DNAJB6基因突变所致肌病临床表现存在异质性,同一家系可表现为不同的临床亚型。结论DNAJB6基因突变可导致肢带型肌营养不良症和远端型肌病两种表型,肌肉病理均呈现镶边空泡和肌营养不良样改变。该家系进一步扩展了DNAJB6基因突变的表型谱。     

D uchenne 型肌营养不良家系的临床及分子遗传学研究

目的：探讨Duchenne型肌营养不良（DMD）家系的临床及分子遗传学特征。方法收集并分析我院收治的2个DMD家系临床资料和基因检测结果,并结合既往相关文献,回顾该病在临床表现、分子遗传学等方面的特点。结果DMD儿童期隐匿起病,进行性加重,以肌无力、肌萎缩为特点,可伴肌肉假性肥大,血清肌酶水平异常增高,肌电图呈肌源性损害,肌肉活检呈肌病特征。本文报道的2个家系经基因检测家系1先证者为DMD基因的第3～21号外显子缺失,家系2先证者则为第8、9外显子重复突变,2个家系中的先证者基因均为纯合突变,且其母亲均为致病基因的携带者,符合X染色体隐性遗传的规律。结论早期识别DMD的临床特征有助于提高该病的诊断水平,基因检测是一种确诊DMD快速、有效的方法。     

散发性眼咽远端型肌病的临床、肌肉影像与电生理特点

目的探讨眼咽远端型肌病(oculopharyngodistal myopathy,OPDM)的临床、电生理及肌肉核磁影像特点及病理、分子遗传学特点。方法报告1例临床诊断OPDM的临床特点、肌电图、肌肉核磁及病理分析结果、分子遗传学资料,对受累肌肉分布情况及肌电图改变,结合文献进行比较分析。结果患者25岁发病,肌肉受累顺序先后为:眼肌、咽喉肌、肢体远端、双下肢近端,肌酸激酶轻度升高。心脏超声:左室增大,二尖瓣轻度反流,左室舒张功能下降。肌电图显示:脱髓鞘性周围神经病,肌源性损害,为混合性损害。肌肉病理显示:肌源性损害伴镶边空泡肌纤维、可疑线粒体代谢异常。肌肉核磁:小腿脂肪化明显重于大腿,小腿以后群肌受累为主。二代测序未发现已知的远端性肌病、肌营养不良、肌原纤维肌病、空泡性肌病基因突变。结论该患者为散发病例,OPDM作为一类独立表型的肌病,以肌肉受累为主,可以出现脱髓鞘性周围神经损害、心脏受累等多系统表现。     

慢性进行性眼外肌麻痹5型合并假肥大型肌营养不良征象患者临床与遗传学特点北大核心CSCD

目的分析常染色体显性遗传慢性进行性眼外肌麻痹(autosomal dominant chronic progressive external ophthalmoplegia, ad CPEO)5型(PEOA5)合并假肥大型肌营养不良(becker muscular dystrophy,BMD)征象病例的临床和遗传学特点。方法家族谱系调查结合肌电图、肌肉活检和基因检测,进行整合分析。结果先证者血清肌酸激酶(CK)值29485U/L,血乳酸2.5 mmol/L,肌电图示肌源性损害。基因检测发现RRM 2B基因外显子1的序列变异c.132G> A(p.W44X)杂合突变和DMD基因外显子6的序列变异c.431T> A(p.V144 D)半合子变异。先证者父母亲无临床症状。母亲携带RRM 2B基因外显子1的序列变异c.132G> A(p.W44X)杂合突变,父亲两个变异均未携带。结论基因分析和肌肉活检是诊断CPEO、BMD的可靠方法,有助于明确诊断不同类型的肌病。     

伴神经源性损害的非炎性肌病临床与电生理特点

目的探究伴神经源性损害的非炎性肌病患者临床及电生理特点。方法回顾性收集自2015至2017年我院明确诊断为肌肉疾病且在我院肌电图室完成常规肌电图检查的所有患者,分析伴神经源性损害且诊断为非炎性肌病患者的临床及电生理特点。结果共收集经基因检测或肌肉活检明确诊断为肌肉疾病患者110例,肌电图出现神经源性损害者为10例,其中出现神经源性损害且为非炎性肌病者4例。上述4例患者分别为1例脂质沉积性肌病、1例中央轴空病、1例包涵体肌病及1例Welander型远端型肌病;肌电图均合并神经源性损害,同时伴或不伴周围神经损害。结论少数非炎性肌病患者肌电图可出现神经源性损害,肌电图不能作为诊断肌肉疾病的单独标准。     

慢性进行性眼外肌麻痹5型合并假肥大型肌营养不良征象患者临床与遗传学特点

目的分析常染色体显性遗传慢性进行性眼外肌麻痹(autosomal dominant chronic progressive external ophthalmoplegia, ad CPEO)5型(PEOA5)合并假肥大型肌营养不良(becker muscular dystrophy,BMD)征象病例的临床和遗传学特点。方法家族谱系调查结合肌电图、肌肉活检和基因检测,进行整合分析。结果先证者血清肌酸激酶(CK)值29485U/L,血乳酸2.5 mmol/L,肌电图示肌源性损害。基因检测发现RRM 2B基因外显子1的序列变异c.132G A(p.W44X)杂合突变和DMD基因外显子6的序列变异c.431T A(p.V144 D)半合子变异。先证者父母亲无临床症状。母亲携带RRM 2B基因外显子1的序列变异c.132G A(p.W44X)杂合突变,父亲两个变异均未携带。结论基因分析和肌肉活检是诊断CPEO、BMD的可靠方法,有助于明确诊断不同类型的肌病。     

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.     

肌活检在肌病诊断准确性的临床研究-单中心1年期间56例患者的回顾性分析

目的 探讨肌肉活体组织检查(肌活检)的病理表现并结合临床、电生理、肌肉影像学及相关实验室检查在肌肉疾病中的诊断价值。方法 收集2017年7月-2018年7月在本院行肌活检的56例患者,分析肌肉病理学与人口学、肌电图、肌肉磁共振、血清肌酸激酶、相关抗体和基因检测的相关性,并评估其诊断价值。结果 ①男36例,女20例,年龄5～69岁、平均年龄(39.2±18.6)岁; ②肌电图显示肌源性损害者占83.6%(46/55),其中6例合并强直电位,6例合并神经源损害; 可疑肌源性损害12.7%(7/55); 单纯神经源性损害1.8%(1/55); 正常1.8%(1/55); ③肌肉磁共振异常率87.9%(29/33); 肌酸激酶升高者60%(33/55),中位823[349, 2505.5] U/L; 4例进行肌炎相关抗体检查者3例异常; 17例进行基因检查者12例提示肌病诊断,其中仅6例家族史阳性; ④通过肌肉组织病理检查并结合临床、抗体和基因检测80.4%的患者(45/56)能够明确肌病诊断,明显高于肌活检之前(23.2%)(P<0.01)。结论 肌活检能明显提高肌病的准确诊断率。     

Ullrich型先天性肌营养不良的临床特点(附1例报告)

目的探讨Ullrich型先天性肌营养不良的临床及病理学特点。方法回顾性分析1例Ullrich型先天性肌营养不良患儿的临床资料,并结合相关文献进行复习。结果患儿自出生起肌张力低下,伴有近端关节挛缩、远端关节弹性过度。生化检查示血磷酸肌酸激酶轻度增高。EMG示肌源性损害(近端肌)肌电改变为主,伴轻度神经源损害(下肢远端肌)。基因二代测序示存在COL6A3基因杂合核苷酸变异,为剪切变异;其父母未见异常。肌肉病理示骨骼肌呈肌营养不良样病理改变。肌肉MRI示双侧小腿及大腿肌肉呈弥漫脂肪浸润伴水肿改变,肌营养不良可能。结论本例患者为杂合子新生突变,是先天性肌营养不良的一个亚型。临床表现以近端关节挛缩、远端关节弹性过度为主要特点。EMG、基因、肌肉病理及肌肉MRI检查有助于本病的诊断。     

Autosomal recessive Bethlem myopathy: A clinical,genetic and functional study

Bethlem myopathy represents the milder form of the spectrum of Collagen VI-related dystrophies, which are characterized by a clinical continuum between the two extremities, the Bethlem myopathy and the Ullrich congenital muscular dystrophy, and include less defined intermediate phenotypes. Bethlem myopathy is mainly an autosomal dominant disorder and the causing mutations occur in the COL6A genes encoding for the α1 (COL6A1), α2 (COL6A2) and α3 (COL6A3) chains. However, few cases of recessive inheritance have been also reported. We here describe clinical, genetic and functional findings in a recessive Bethlem myopathy family harbouring two novel pathogenic mutations in the COL6A2 gene. Two adult siblings presented with muscle weakness and wasting, elbows and Achilles tendon retractions, lumbar hyperlordosis, waddling gait and positive Gowers' sign. Muscle biopsy showed a dystrophic pattern. Molecular analysis of the COL6A2 gene revealed the novel paternally-inherited nonsense p.Gln889* mutation and the maternally-inherited p.Pro260_Lys261insProPro small insertion. Fibroblast studies in both affected patients showed the concomitant reduction in the amount of normal Collagen VI (p.Gln889*) and impairment of Collagen VI secretion and assembly (p.Pro260_Lys261insProPro). Each of the two variants behave as a recessive mutation as shown by the asymptomatic heterozygous parents, while their concomitant effects determined a relatively mild Bethlem myopathy phenotype. This study confirms the occurrence of recessive inherited Bethlem myopathy and expands the genetic heterogeneity of this group of muscle diseases.     

Variable penetrance of COL6A1 null mutations: implications for prenatal diagnosis and genetic counselling in Ullrich congenital muscular dystrophy families

Collagen VI mutations cause mild Bethlem myopathy and severe, progressive Ullrich congenital muscular dystrophy (UCMD). We identified a novel homozygous COL6A1 premature termination mutation in a UCMD patient that causes nonsense-mediated mRNA decay. Collagen VI microfibrils cannot be detected in muscle or fibroblasts. The parents are heterozygous carriers of the mutation and their fibroblasts produce reduced amounts of collagen VI. The molecular findings in the parents are analogous to those reported for a heterozygous COL6A1 premature termination mutation that causes Bethlem myopathy. However, the parents of our UCMD proband are clinically normal. The proband's brother, also a carrier, has clinical features consistent with a mild collagen VI phenotype. Following a request for prenatal diagnosis in a subsequent pregnancy we found the fetus was a heterozygous carrier indicating that it would not be affected with severe UCMD. COL6A1 premature termination mutations exhibit variable penetrance necessitating a cautious approach to genetic counselling.     

Autosomal recessive inheritance of classic Bethlem myopathy

Mutations in the collagen VI genes (COL6A1, COL6A2 and COL6A3) result in Ullrich congenital muscular dystrophy (CMD), Bethlem myopathy or phenotypes intermediate between Ullrich CMD and Bethlem myopathy. While Ullrich CMD can be caused by either recessively or dominantly acting mutations, Bethlem myopathy has thus far been described as an exclusively autosomal dominant condition. We report two adult siblings with classic Bethlem myopathy who are compound heterozygous for a single nucleotide deletion (exon 23; c.1770delG), leading to in-frame skipping of exon 23 on the maternal allele, and a missense mutation p.R830W in exon 28 on the paternal allele. The parents are carriers of the respective mutations and are clinically unaffected. The exon skipping mutation in exon 23 results in a chain incapable of heterotrimeric assembly, while p.R830W likely ameliorates the phenotype into the Bethlem range. Thus, autosomal recessive inheritance can also underlie Bethlem myopathy, supporting the notion that Ullrich CMD and Bethlem myopathy are part of a common clinical and genetic spectrum.     

Differentiating Emery-Dreifuss muscular dystrophy and collagen VI-related myopathies using a specific CT scanner pattern

Bethlem myopathy and Ullrich congenital muscular dystrophy are part of the heterogeneous group of collagen VI-related muscle disorders. They are caused by mutations in collagen VI (ColVI) genes (COL6A1, COL6A2, and COL6A3) while LMNA mutations cause autosomal dominant Emery-Dreifuss muscular dystrophy. A muscular dystrophy pattern and contractures are found in all three conditions, making differential diagnosis difficult especially in young patients when cardiomyopathy is absent.We retrospectively assessed upper and lower limb muscle CT scans in 14 Bethlem/Ullrich patients and 13 Emery-Dreifuss patients with identified mutations.CT was able to differentiate Emery-Dreifuss muscular dystrophy from ColVI-related myopathies in selected thigh muscles and to a lesser extent calves muscles: rectus femoris fatty infiltration was selectively present in Bethlem/Ullrich patients while posterior thigh muscles infiltration was more prominently found in Emery-Dreifuss patients. A more severe fatty infiltration particularly in the leg posterior compartment was found in the Emery-Dreifuss group.     

Collagen XII myopathy with rectus femoris atrophy and collagen XII retention in fibroblasts

Introduction: Mutation in the collagen XII gene (COL12A1) was recently reported to induce Bethlem myopathy. We describe a family affected by collagen XII‐related myopathy in 3 generations. Methods: Systematic interview, clinical examination, skin biopsies, and MRI of muscle were used. Results: The phenotype was characterized by neonatal hypotonia, contractures, and delayed motor development followed by resolution of contractures and a motor performance limited by reduced endurance. DNA analyses revealed a novel donor splice‐site mutation in COL12A1 (c.8100 + 2T>C), which segregated with clinical affection and abnormal collagen XII retention in fibroblasts. MRI disclosed a selective wasting of the rectus femoris muscle. Discussion: COL12A1 mutations should be considered in patients with a mild Bethlem phenotype who present with selective wasting of the rectus femoris, absence of the outside‐in phenomenon on MRI, and abnormal collagen XII retention in fibroblasts. Muscle Nerve 57 : 1026–1030, 2018     

Electrocardiographic findings in mdx mice: a cardiac phenotype of Duchenne muscular dystrophy

Bethlem myopathy is an early-onset benign myopathy characterized by proximal muscular weakness and multiple flexion contractures. It is a dominantly inherited disorder associated with mutations in the three COL6 genes encoding type VI collagen. We detected a g-->a substitution at +1 position of COL6A1 intron 3 in a four-generation Italian family affected by a mild form of Bethlem myopathy. The mutation results in the activation of a cryptic splice donor site at the 3' end of exon 3, leading to the loss of 66 nucleotides and an "in-frame" deletion of 22 amino acids in the NH2-domain. Molecular analysis on fibroblasts of the propositus showed that the mutated mRNA was present and stable, but the mutated protein could not be detected. Western blot and immunofluorescence analyses showed a decreased level of collagen VI synthesis and deposition in fibroblasts of the propositus. Together, the results suggest that the mutated protein was highly unstable and rapidly degraded, and that the mild phenotype was caused by a reduced amount of normal collagen VI microfibrils. In addition, we demonstrated that lymphocytes can be used for the first mutation screening analysis of patients with Bethlem myopathy.     

Collagen VI-related muscle disorders

Collagen VI-related muscle disorders include severe Ullrich's disease (Ullrich congenital muscular dystrophy:UCMD) and milder Bethlem myopathy. Mutations in the 3 collagen VI genes, namely, COL6A1, COL6A2, and COL6A3, cause both diseases. UCMD is inherited in an autosomal recessive manner, and de novo dominant mutations are also reported. Bethlem myopathy is usually inherited in an autosomal dominant manner, but a rare autosomal recessive inheritance has recently been reported. Patients with UCMD have generalized muscle weakness, multiple contractures of the proximal joints, and hyperextensibility of the distal joints. Bethlem myopathy is characterized by a combination of proximal muscle weakness and contractures of finger, elbow, and ankle joints. Because intermediate phenotypes occur, UCMD and Bethlem myopathy should be considered diseases in a continuous spectrum of collagen VI-related muscle disorders. Abnormalities of cell adhesion, regeneration, mitochondrial permeability transition pore, and autophagy have been reported in UCMD. Respiratory surveillance for nocturnal hypoventilation and proper respirator implementation are crinical management considerations in UCMD. Orthopedic assessment in necessary if surgery for Achilles tendon contractures is being considered in patient with Bethlem myopathy. We evaluated the role of nonsense-mediated mRNA decay (NMD) in UCMD associated with a premature termination codon in the COL6A2 gene, which caused the loss of collagen VI. A pharmacological block of NMD caused upregulation of the mutant collagen VI and partially functional extracellular matrix formation. Cyclosporin A has been reported to correct mitochondrial dysfunction and muscle apoptosis in patients with collagen VI myopathies, and a pilot trial of cyclosporin A was carried out.     

Collagenopathy (Ullrich congenital muscular dystrophy, Bethlem myopathy)]

Collagenopathies with collagen VI mutations include Ullrich congenital muscular dystrophy (Ullrich's disease) and Bethlem myopathy. Patients with Ullrich's disease have generalized muscle weakness, multiple contractures of the proximal joints and hyperextensibility of the distal joints. Bethlem myopathy is characterized by the combination of proximal muscle weakness and contractures of finger, elbow, and ankle joints. We found for the first time a deficiency of collagen VI in Ullrich's disease. Furthermore, we found an abnormality of cell adhesion and abnormal regeneration or maturation in Ullrich's disease. Mutations in the genes COL6A1, COL6A2, COL6A3 are associated with Ullrich's disease and Bethlem myopathy. Bethlem myopathy is inherited in an autosomal dominant manner and Ullrich's disease usually in an autosomal recessive manner. Recently, de novo dominant mutations are reported in Ullrich's disease. We evaluated the role of nonsense-mediated mRNA decay (NMD) in Ullrich's disease that has a frameshift mutation with a premature termination codon in the COL6A2 gene causing the loss of collagen VI. The pharmacological block of NMD caused upregulation of the mutant collagen VI and partially functional extracellular matrix formation. Our results suggest that NMD inhibitors can be used as a therapeutic tool to rescue some human genetic diseases exacerbated by NMD.     

Novel mutations in collagen VI genes: expansion of the Bethlem myopathy phenotype

OBJECTIVE: To investigate the molecular basis of autosomal dominant limb-girdle muscular dystrophy (AD-LGMD) in three large new families. METHODS AND RESULTS: Genome-wide linkage was performed to show that the causative gene in all three families localized to chromosome 21q22.3 (Zmax = 10.3; theta = 0). This region contained the collagen VI alpha1 and alpha2 genes, which have been previously shown to harbor mutations causing a relatively mild congenital myopathy with contractures (Bethlem myopathy). Screening of the collagen VI alpha1 and alpha2 genes revealed novel, causative mutations in each family (COL6A1-K121R, G341D; COL6A2-D620N); two of these mutations were in novel regions of the proteins not previously associated with disease. Collagen VI is a ubiquitously expressed component of connective tissue; however, both limb-girdle muscular dystrophy and Bethlem myopathy patients show symptoms restricted to skeletal muscle. To address the muscle-specific symptoms resulting from collagen VI mutations, the authors studied three patient muscle biopsies at the molecular level (protein expression). A marked reduction of laminin beta1 protein in the myofiber basal lamina in all biopsies was found, although this protein was expressed normally in the neighboring capillary basal laminae. CONCLUSIONS: The authors' studies widen the clinical spectrum of Bethlem myopathy and suggest collagen VI etiology should be investigated in dominant limb-girdle muscular dystrophy. The authors hypothesize that collagen VI mutations lead to muscle-specific defects of the basal lamina, and may explain the muscle-specific symptoms of Bethlem and limb-girdle muscular dystrophy patients with collagen VI mutations.     

Muscle MRI in Ullrich congenital muscular dystrophy and Bethlem myopathy

The aim of this study was to evaluate the spectrum of muscle involvement on Magnetic Resonance Imaging (MRI) in patients with collagen VI related disorders. Nineteen patients with genetically confirmed collagen VI related disorders, 10 with Bethlem myopathy and 9 with Ullrich congenital muscular dystrophy (CMD), had muscle MRI of their legs using T1 sequences through calves and thighs. In patients with Bethlem myopathy the vasti muscles appeared to be the most frequently and most strikingly affected thigh muscles, with a rim of abnormal signal at the periphery of each muscle and relative sparing of the central part. Another frequent finding was the presence of a peculiar involvement of the rectus femoris with a central area of abnormal signal within the muscle. Patients with Ullrich CMD had a more diffuse involvement of the thigh muscles with relative sparing of sartorius, gracilis and adductor longus. In 8 of the 9 patients with Ullrich CMD, we also observed the peripheral rim of the vastus lateralis and the central area in the rectus femoris observed in patients with Bethlem myopathy. At calf level the results were more variable but a significant proportion of patients with both Bethlem myopathy (8/10) and Ullrich CMD (6/9) showed a rim of abnormal signal at the periphery of soleus and gastrocnemii. Bethlem myopathy and Ullrich CMD patients have distinct patterns of muscle involvement on MRI with some overlap between the two forms. Our results suggest that muscle MR may be used, as an additional tool, to identify patients with collagen VI related disorders. This information is even more important in the patients with a typical Ullrich CMD clinical phenotype but with normal collagen expression of VI in muscle and/or skin.