Background: X-linked Charcot-Marie-Tooth type 1 (CMT1X) disease is one of the most common forms of inherited neuropathy caused by mutations in the gap junction beta-1 protein (GJB1) gene (also known as connexin 32). This study presented the clinical and genetic features of a series of Chinese patients with GJB1 gene mutations. Methods: A total of 22 patients from unrelated families, who were referred to Department of Neurology, Peking University First Hospital from January 2005 to January 2016, were identified with GJB1 mutations. Their clinical records and laboratory findings were retrospectively collected and reviewed. Mutations in the GJB1 gene were analyzed by targeted next-generation sequencing (NGS). Nucleotide alternations were confirmed with Sanger sequencing. Results: The CMT1X patients predominantly showed distal muscle weakness of lower limbs with mild sensory disturbance. The mean age of onset was 15.6 ± 8.7 years (ranging from 1 year to 42 years). The sudden onset of cerebral symptoms appeared in four patients (18.2%); two were initial symptoms. One case had constant central nervous system (CNS) signs. There were 19 different heterozygous mutations, including 15 known mutations and four novel mutations (c.115G>T, c.380T>A, c.263C>A, and c.818_819insGGGCT). Among the 22 Chinese patients with CMT1X, the frequency of the GJB1 mutation was 4.5% in transmembrane domain 1 (TM1), 4.5% in TM2, 22.7% in TM3, 9.1% in TM4, 4.5% in extracellular 1 (EC1), 27.3% in EC2, 9.1% in intracellular loop, 13.6% in the N-terminal domain, and 4.5% in the C-terminal domain. CMT1X with CNS impairment appeared in five (22.7%) of these patients. Conclusions: This study indicated that CNS impairment was not rare in Chinese CMT1X patients. Mutations in the EC2 domain of the GJB1 gene were hotspot in Chinese CMT1X patients.

This study aimed to study the diagnostic value of targeted next-generation sequencing (NGS) in limb-girdle muscular dystrophies (LGMDs), and investigate the mutational spectrum of Chinese LGMD patients. We performed targeted NGS covering 420 genes in 180 patients who were consecutively suspected of LGMDs and underwent muscle biopsies from January 2013 to May 2015. The association between genotype and myopathological profiles was analyzed in the genetically confirmed LGMD patients. With targeted NGS, one or more rare variants were detected in 138 patients, of whom 113 had causative mutations, 10 sporadic patients had one pathogenic heterozygous mutation related to a recessive pattern of LGMDs, and 15 had variants of uncertain significance. No disease-causing mutation was found in the remaining 42 patients. Combined with the myopathological findings, we achieved a positive genetic diagnostic rate as 68.3% (123/180). Totally 105 patients were diagnosed as LGMDs with genetic basis. Among these 105 patients, the most common subtypes were LGMD2B in 52 (49.5%), LGMD2A in 26 (24.8%) and LGMD 2D in eight (7.6%), followed by LGMD1B in seven (6.7%), LGMD1E in four (3.8%), LGMD2I in three (2.9%), and LGMD2E, 2F, 2H, 2K, 2L in one patient (1.0%), respectively. Although some characteristic pathological changes may suggest certain LGMD subtypes, both heterogeneous findings in a certain subtype and overlapping presentations among different subtypes were not uncommon. The application of NGS, together with thorough clinical and myopathological evaluation, can substantially improve the molecular diagnostic rate in LGMDs. Confirming the genetic diagnosis in LGMD patients can help improve our understanding of their myopathological changes.

Introduction: The aim of this study was to evaluate the pattern of thigh muscle MRI changes in a large cohort of patients with dysferlinopathy. Methods: MRI of the thigh was performed in 60 patients. We correlated the scale of muscle involvement on MRI with the modified Gardner‐Medwin and Walton (GM‐W) scale and disease duration. We also analyzed the relationship between muscle changes and genetic mutations. Results: Fatty infiltration and edema were observed in 95.50% and 86.67% of patients, respectively. The hamstring muscles had the highest frequency and mean score of fatty infiltration, although a posterior‐dominant pattern was found in only 56%. Edema most commonly and severely affected the quadriceps and adductor magnus muscles. Fatty infiltration score correlated positively with disease duration and GM‐W scale. Conclusions: The pattern of fatty infiltration was heterogeneous in dysferlinopathy patients. Muscle edema was common. Fatty infiltration can be used to assess disease progression. Muscle Nerve 54: 1072–1079, 2016

Background: Collagen VI-related myopathies are autosomal dominant and recessive hereditary myopathies, mainly including Ullrich congenital muscular dystrophy (UCMD) and Bethlem myopathy (BM). Muscle magnetic resonance imaging (MRI) has been widely used to diagnosis muscular disorders. The purpose of this study was to evaluate the diagnostic value of thigh muscles MRI for collagen VI-related myopathies. Methods: Eleven patients with collagen VI gene mutation-related myopathies were enrolled in this study. MRI of the thigh muscles was performed in all patients with collagen VI gene mutation-related myopathies and in 361 patients with other neuromuscular disorders (disease controls). T1-weighted images were used to assess fatty infiltration of the muscles using a modified Mercuri's scale. We assessed the sensitivity and specificity of the MRI features of collagen VI-related myopathies. The relationship between fatty infiltration of muscles and specific collagen VI gene mutations was also investigated. Results: Eleven patients with collagen VI gene mutation-related myopathies included six UCMD patients and five BM patients. There was no significant difference between UCMD and BM patients in the fatty infiltration of each thigh muscle except sartorius (P = 0.033); therefore, we combined the UCMD and BM data. Mean fatty infiltration scores were 3.1 and 3.0 in adductor magnus and gluteus maximus, while the scores were 1.3, 1.3, and 1.5 in gracilis, adductor longus, and sartorius, respectively. A "target" sign in rectus femoris (RF) was present in seven cases, and a "sandwich" sign in vastus lateralis (VL) was present in ten cases. The "target" and "sandwich" signs had sensitivities of 63.6% and 90.9% and specificities of 97.3% and 96.9% for the diagnosis of collagen VI-related myopathies, respectively. Fatty infiltration scores were 2.0–3.0 in seven patients with mutations in the triple-helical domain, and 1.0–1.5 in three of four patients with mutations in the N- or C-domain of the collagen VI genes. Conclusions: The "target" sign in RF and "sandwich" sign in VL are common MRI features and are useful for the diagnosis of collagen VI-related myopathies. The severity of fatty infiltration of muscles may have a relationship with the mutation location of collagen VI gene.

Background: Dysferlinopathy is caused by mutations in the dysferlin (DYSF) gene. Here, we described the genetic features of a large cohort of Chinese patients with this disease. Methods: Eighty-nine index patients were included in the study. DYSF gene analysis was performed by Sanger sequencing in 41 patients and targeted next generation sequencing (NGS) in 48 patients. Multiplex ligation-dependent probe amplification (MLPA) was performed to detect exon duplication/deletion in patients with only one pathogenic mutation. Results: Among the 89 index patients, 79 patients were demonstrated to carry two disease-causing (73 cases) or possibly disease-causing mutations (6 cases), including 26 patients with homozygous mutations. We identified 105 different mutations, including 59 novel ones. Notably, in 13 patients in whom only one pathogenic mutation was initially found by Sanger sequencing or NGS, 3 were further identified to carry exon deletions by MLPA. The mutations identified in this study appeared to cluster in the N-terminal region. Mutation types included missense mutations (30.06%), nonsense mutations (17.18%), frameshift mutations (30.67%), in-frame deletions (2.45%), intronic mutations (17.79%), and exonic rearrangement (1.84%). No genotype-phenotype correlation was identified. Conclusions: DYSF mutations in Chinese patients clustered in the N-terminal region of the gene. Exonic rearrangements were found in 23% of patients with only one pathogenic mutation identified by Sanger sequencing or NGS. The novel mutations found in this study greatly expanded the mutational spectrum of dysferlinopathy.

目的 总结几种常见类型先天性肌病大腿肌肉MRI的改变规律,评价其诊断价值.方法 选取通过肌肉病理检查确诊的先天性肌肉病患者12例,包括杆状体肌病5例、轴空病4例、中央核肌病3例,其中男性9例,女性3例,平均年龄(19.6±10.1)岁,平均病程(14.1±11.7)年,3例患者家系内有类似发病者.所有患者行大腿骨骼肌MRI检查,行T1WI序列观察骨骼肌脂肪化,行STIR序列观察骨骼肌水肿情况,对大腿12块肌肉脂肪化和水肿程度进行6级评分.结果 先天性肌病患者大腿不同肌肉脂肪化评分平均在(1.75±1.09)分到(3.67±0.85)分之间,大腿肌肉平均脂肪化总分分别为中央核肌病(41.00±11.34)分,多发微小轴空病(31.25±4.32)分,杆状体肌病(22.8±3.71)分,且不同类型先天性肌病肌肉脂肪化分布形式存在差异.9例出现大腿肌肉萎缩,其中5例为弥漫性萎缩,4例为后群及内侧群肌肉萎缩.所有患者均不存在肌肉肥大.3例皮下筋膜水肿,1例股四头肌水肿.结论 不同类型先天性肌病脂肪化及萎缩程度存在明显差异.大腿肌肉无肥大是其共同特点.

Recently, mutations in the inverted formin 2 (INF2) gene have been indentified in patients with dominant inherited intermediate Charcot-Marie-Tooth neuropathy (DI-CMT) with focal segmental glomerulosclerosis (FSGS). We report clinical and nerve pathological changes in two Chinese patients. Case 1 is 27 years old and presented with distal muscle weakness and atrophy of legs at the age of 13 and renal failure at the age of 26. Three of his family members died due to pure renal failure. Case 2 is 22 years old and presented with distal muscle weakness and atrophy of the legs with transient attacks of difficulty in speaking at age 17. Proteinuria was found by routine urine test at the same time. Sural nerve biopsy revealed moderate-to-severe loss of myelinated fibers with union bulbs and regeneration clusters in both patients. Ultrastructurally, numerous elongated extensions of Schwann cells of unmyelinated fibers could be seen in both patients. INF2 gene mutation screening revealed c.451 T>C in case 1 and c.341 G>A in case 2. This is the first report of Chinese patients with INF2-related DI-CMT. The c.451 T>C mutant was responsible for both isolated FSGS and a dual phenotype of FSGS and neuropathy within one family. Intrafamilial variability can be found with the same INF2 mutation. The CNS manifestations further broadened the clinical spectrum of INF2- associated disorders.

Background: The purpose of this study was to evaluate the diagnostic value of the trefoil (three leaflets formed by relative sparing of the sartorius, gracilis, and adductor longus) with single fruit sign (relative sparing of the semitendinosus) in the evaluation of thigh muscle magnetic resonance imaging (MRI) for dystrophinopathies.Methods: Five examiners blinded to any clinical data analyzed muscle MRI scans from 166 patients with dystrophinopathies (124 cases confirmed genetically and 42 cases confirmed by immunohistochemistry) and from 244 control patients, all treated in our hospital from 2011 to 2014. The controls were patients with other neuromuscular disorders and with dystrophinopathies excluded by genetic testing and/or muscle biopsy. Examiners assessed the presence or absence of the trefoil with single fruit sign approximately at the middle thigh cross-section. Results were analyzed for diagnostic accuracy and inter-examiner agreement.Results: Sensitivity of the trefoil with single fruit sign for all patients with dystrophinopathies was 41.6% (95% confidence interval (CI) of 34.0-49.5). However, specificity was 99.2% (95% CI 97.1-99.9). The positive predictive value (PPV) was 97.2% and negative predictive value (NPV) was 71.4%. Inter-examiner agreement was substantial (Kappa = 0.66). The 69 dystrophinopathy patients whose MRIs exhibited the sign were significantly older than the 97 dystrophinopathy patients whose MRIs did not (Z = -3.970, p < 0.001).Conclusions: The trefoil with single fruit sign is a potential imaging marker for diagnosis of dystrophinopathies. (C) 2015 Elsevier Ireland Ltd. All rights reserved.

Objective To investigate the characteristics of muscle edema and fatty infiltration in thighs and relationship with clinical symptoms in Chinese patients with different phenotypes of dysferlinopathy.Methods A total of 32 patients were enrolled , including 13 limb-girdle muscular dystrophy 2B (LGMD2B), 13 Miyoshi myopathy (MM), 4 proximodistal myopathy and 2 hyper-creatine-kinase-emia.Clinical symptoms were evaluated using modified Gardner-Medwin and Walton ( GM-W) score.Muscle MRI was performed in thighs to observe fatty infiltration and edema.We then compared the age of onset , disease duration, GM-W score, muscle edema and muscle fatty infiltration between LGMD 2B and MM groups,and the relationship of muscle edema score and fatty infiltration score with disease duration and GM-W score in all patients.Results The median GM-W score was 4.00 (2.00,5.00) in all patients, 4.00 (3.00,4.50)in LGMD2B and 4.00(2.00,5.00)in MM, respectively.Muscle fatty infiltration appeared in 30 cases (93.75%), with the same pattern in LGMD2B and MM.The mean fatty infiltration score was 28.20 ±12.86 in all patients, 28.50 ±13.03 in LGMD2B and 29.00 ±12.63 in MM, respectively.Muscle edema appeared in 26 cases (81.25%) with same pattern in LGMB2B and MM.The mean edema score was 18.36 ±13.60 in all patients, 22.88 ±11.59 in LGMD2B and 16.77 ±13.80 in MM.The age of onset , disease duration, GM-W score, muscle fatty infiltration and edema score were not significantly different between LGMD2B and MM patients.Muscle fatty infiltration score significantly correlated with GM-W score (rs=0.737,P=0.000) and disease duration (rs=0.637,P=0.000).Conclusions Fatty infiltration and edema in thigh muscles are very common in patients with dysferlinopathy , with similar radiological changes in main subtypes.The muscle fatty infiltration can be used as a predictor of disease progression.

Aims Myopathy or neuropathy has been associated with lamivudine/telbivudine therapy in hepatitis B patients. We aim to describe the pathological changes of lamivudine/telbivudine-associated neuromyopathy.Methods We retrospectively recruited six patients who were diagnosed with nucleotide analogues-associated myopathy or neuropathy. Muscle and nerve biopsy were performed, and the specimens were prepared for the light microscopy and electron microscopy. Genomic DNA was extracted from frozen muscle specimens, and the mitochondrial DNA (mtDNA) content was quantified by real-time PCR.Results Recovery of the myopathy can be achieved after the discontinuation or changing the drugs to entecavir. Muscle and nerve biopsy revealed similar changes under either the light or electronic microscopy in all the subjects. Quantitative real-time PCR revealed decrease of mtDNA content in the affected muscle.Conclusions MtDNA depletion results in mitochondrial dysfunction in the lamivudine/telbivudine-associated neuromyopathy. Myopathy was characterised by mitochondrial dysfunction accompanied with neurogenic damage due to axonal neuropathy. Ultrastructure changes of mitochondria included vacuolisation, simplification of the cristae and homogenised matrix.

It has been implicated that Dux4 plays crucial roles in development of facioscapulohumeral dystrophy. But the underlying myopathic mechanisms and related down-stream events of this retrogene were far from clear. Here, we reported that overexpression of Dux4 in a cell model TE671 reduced cell proliferation rate, and increased G1 phase accumulation. We also determined the impact of Dux4 on p53/p21 signal pathway, which controls the checkpoint in cell cycle progression. Overexpression of Dux4 increased p21 mRNA and protein level, while expression of p53, phospho-p53 remained unchanged. Silencing p21 rescued Dux4 mediated proliferation defect and cell cycle arrest. Furthermore, we demonstrated that enhanced Dux4 expression increased p21 promoter activity and elevated expression of Sp1 transcription factor. Mutation of Sp1 binding site decreased dux4 induced p21 promoter activation. Chromatin immunoprecipitation (ChIP) assays confirmed the Dux4-induced binding of Sp1 to p21 promoter in vivo. These results suggest that Dux4 might induce proliferation inhibition and G1 phase arrest through upregulation of p21.