Background Nemaline myopathy, the most common of the congenital myopathies, is caused by various genetic mutations. In this study, we attempted to investigate the clinical features, muscle pathology and genetic features of 15 patients with nemaline myopathy. Results Among the 15 patients, there were 9 (60.00%) males and 6 (40.00%) females, and 9 (60.00%) of them came from three families respectively. The age of seeing a doctor ranged from 9 to 52 years old, the age of onset was from 5 to 23 years old, and the duration of disease ranged from 3 to 35 years. Ten out of the 15 patients had high arched palate and elongated face. Only one patient had mild respiratory muscle involvement and none had dysphagia. Muscle biopsies were performed in 9 out of the 15 patients. Pathologically, muscle fibers of different sizes, atrophic muscle fibers and compensatory hypertrophic fibers could be found, and occasionally degenerated and necrotic muscle fibers were observed. Different degrees of nemaline bodies aggregation could be seen in all 9 patients. The distribution of type I and type II muscle fibers were significantly abnormal in patients with nemaline myopathy caused by NEB gene, however, it was basically normal in patients with nemaline myopathy caused by TPM3 gene and ACTA1 gene. Electron microscopic analysis of 6 patients showed that nemaline bodies aggregated between myofibrils were found in 5(83.33%) cases, and most of them were located near the Z band, but no intranuclear rods were found. The gene analysis of 15 NM patients showed that three NM-related genes were harbored, including 11 (73.33%) patients with NEB, 3 (20.00%) patients with TPM3, and 1 (6.67%) patient with ACTA1, respectively. A total of 12 mutation sites were identified and included 10 (83.33%) mutations in exon and 2(16.67%) mutations in intron. Conclusions The clinical phenotype of nemaline myopathy is highly heterogeneous. Muscle pathology shows that nemaline bodies aggregation is an important feature for the diagnosis of NM. NEB is the most frequent causative gene in this cohort. The splicing mutation, c.21522 + 3A > G may be the hotspot mutation of the NEB gene in Chinese NM patients.

目的 探讨杆状体肌病的临床特点、肌肉MRI改变和基因突变.方法 回顾性分析1例NEB基因新复合杂合突变致儿童型杆状体肌病患者的临床资料.结果 本例患者为男性,6岁发病,以双下肢远端无力起病,逐渐向近端发展,14岁行肌肉活检在肌纤维内发现大量杆状体而被确诊,29岁复诊时做基因检测明确为NEB基因突变.双下肢肌肉MRI提示双侧股外侧肌、股中间肌、大收肌萎缩并脂肪变性.双侧比目鱼肌脂肪变性并萎缩,腓肠肌内侧头和胫前肌水肿.与文献报道不同的是本例患者双下肢远端无力明显重于近端,且发病23年仍未累及颈肌和上肢肌肉.基因检测发现NEB基因有两处杂合突变,c.2549delA发生移码变异,c.21522+3A>G发生点突变,家系验证结果显示这两处杂合突变分别来自其父亲和母亲.目前文献报道NEB基因已发现有312种突变,本例发生在第27号外显子上的c.2549delA突变,在人类基因数据库和HGMDpro数据库中亦均未见有报道,为新发现的突变位点.结论 杆状体肌病临床表型异质性较大,肌肉病理和基因检测是诊断的重要依据,c.2549delA为NEB基因新发的突变位点.

线粒体神经胃肠型脑肌病(mitochondrial neurogastroint-estinal encephalomyopathy,MNGIE)是一种罕见的常染色体隐性遗传的多系统疾病,由于核基因TYMP突变导致胸苷磷酸化酶(thymidine phosphorylase,TP)缺陷所致[1].TP的活性降低或缺失,可导致脱氧胸苷和脱氧尿嘧啶核苷在组织中的蓄积,引起线粒体功能的异常,从而导致患者出现多系统受累的临床症状.MNGIE典型的临床症状包括严重的胃肠动力障碍、脑白质病变、眼外肌麻痹、周围神经病变和肌肉萎缩[2].自2012年许二赫等首次在国内报道了该病以来[3],目前国内约有13例MNGIE的相关报道[4-8].本文报告1例经肌肉病理与基因检测共同确诊的MNGIE患者,与以往文献报道不同的是本例患者的脑影像不仅有脑白质病变,而且有双侧基底节区和小脑齿状核病变.基因检测发现TYMP基因在7号和10号外显子区域分别有c.914T＞C和c.1319T＞C两处新发的错义突变,扩展了TYMP基因的变异谱系.