中文摘要：

目的探讨microRNA-27a-3p在重症肌无力（myasthenia gravis，MG）患者胸腺组织中的表达水平并分析其临床意义。方法收集2004年12月至2015年2月于哈尔滨医科大学附属第二医院胸外科经手术治疗的19例MG患者的胸腺组织标本作为病例组，17例经手术治疗的非MG患者胸腺组织及心外科先天性心脏病患者手术时切取的胸腺组织标本作为对照组，通过实时荧光定量PCR方法检测，采用Wilcoxon秩和检验分析两组标本中microRNA-27a-3p的表达情况。采用Spearman秩相关分析方法分析MG组胸腺中microRNA-27a-3p的表达水平与定量重症肌无力评分（Quantitative Myasthenia Gravis Score，QMGS）之间的相关性。结果（1）MG患者胸腺中microRNA-27a-3p的表达水平[0．195（0．049，0．714）]显著高于对照组[0．045（0．004，0．088）；Z=-2．646，P=0．008]；（2）19例MG患者中，眼肌型MG（ocular myasthenia gravis，OMG）7例，全身型MG（generalized myasthenia gravis，GMG）12例，与OMG[0．035（0．008，0．103）]相比，GMG患者胸腺中microRNA-27a-3p的表达[0．493（0．157，1．123）]显著上调（Z=-2．620，P=0．009）；（3）microRNA-27a-3p的表达水平与QMGS之间具有正相关性（r=0．576，P=0．010）。结论micmRNA-27a-3p在MG患者胸腺中异常高表达，可能与肌无力的严重程度呈正相关，并与其临床类型有关，但与发病年龄、性别、胸腺病理无明显关联。

英文摘要：

Objective To investigate the expression level of thymus microRNA-27a-3p in patients with myasthenia gravis （MG） and to explore the pathogenesis of MG. Methods Thymus tissue samples from 36 cases were collected from December 2014 to February 2015 in the Second Affiliated Hospital of Harbin Medical University. Nineteen thymus tissue samples of MG group were collected from department of chest surgery, 17 thymus tissue samples of control group were collected from department of chest surgery or congenital heart disease patients from department of cardiac surgery. The expression of microRNA-27a-3p in the thymus from 36 patients was determined by quantitative reverse transcription polymerase chain reaction （qRT-PCR）, using U6 as housekeeping control. The Wilcoxon Rank-Sum test was used to analyze the relative expression of microRNA-27a-3p of the two groups. Spearman rank correlation was used to determine the correlation coefficient between microRNA-27a-3p and Quantitative Myasthenia Gravis Score （QMGS）. Results （1） The expression level of microRNA-27a-3p in thymus was significantly higher in MG group （0. 195 （0. 049,0. 714 ） ） compared with control group （0. 045 （0. 004, 0. 088 ）, Z = -2. 646,P = 0. 008 ）. （2） Nineteen MG patients were included in the study, out of which 7 were ocular myasthenia gravis （OMG） patients and 12 were generalized myasthenia gravis （GMG） patients. The expression of microRNA-27a-3p in GMG patients （0. 493（0. 157, 1. 123） ） was significantly higher than that in OMG patients （0. 035（0. 008,0. 103）, Z = - 2. 620, P = 0. 009 ）. （ 3 ） There was a positive correlation between the expression of microRNA-27a-3p and QMGS （r = 0. 576, P = 0. 010）. Conclusions The expression of microRNA-27a- 3p in thymus is significantly up-regulated in the patients with MG. MicroRNA-27a-3p may be associated with MG severity and significantly elevated in GMG patients compared with OMG patients.