中文摘要：

目的探索补体C3基因rs7951位点多态性与重症肌无力（MG）的易感性和严重程度的相关性。方法纳入475例MG患者和487例健康对照组,采用SNPscanTM多重SNP分型技术对C3基因rs7951位点进行基因分型,比较等位基因和基因型频率在MG组及各亚组（性别、发病年龄、胸腺情况、首发受累范围以及最严重时的Osserman分型和Osterhuis评分）间的分布。结果 rs7951位点检测到CC、CT、TT 3种基因型,MG组T等位基因（118/950,12.4%）高于对照组（92/974,9.4%）,差异有统计学意义（P=0.036,OR=1.360,95%CI 1.019～1.815）。分别在共显性、隐性、显性和加性模型下分析MG组与对照组的基因型频率,发现基因型差异（与CC相比）在显性模型（P=0.044,OR=1.38,95%CI 1.01～1.89）和加性模型（P=0.037,OR=1.36,95%CI 1.02～1.82）下有统计学意义。除了在15～50岁MG亚组与对照组之间,rs7951位点的基因型在其他各MG亚组分布频率的差异无统计学意义。结论补体C3基因rs7951 T等位基因可能与MG易感性相关。

英文摘要：

Objective To explore the association between Complement 3 gene rs7951 polymorphism and the susceptibility and severity of myasthenia gravis （MG）. Methods The rs7951 polymorphisms were determined by SNPscan^TMtechnique. The frequencies of genotypes and alleles were compared between 475 MG patients and 487 healthy controls, as well as among subgroups of MG patients. Subgroups are classified by gender, age of onset, thymoma,involvement at onset of MG, Osserman types and Osterhuis score at the maximal severity during the MG course. Results CC.CT,TT genotypes were determined in SNP rs7951. The frequency of T allele in MG group （ 118/950,12.4% ） was significantly higher than that in the control group （92/974,9.4%） （P = 0. 036, OR = 1. 360,95% CI 1. 019 - 1. 815 ）. The rs7951 genotype frequencies were compared under codominant, recessive, dominant and log-additive model. There were significant difference in the frequencies between case and control under dominant （P = O. 044, OR = 1.38,95% CI 1.01 - 1.89） and log-additive model （P = 0.037,0R = 1.36,95% CI 1.02 -1.82）. There was no significant difference in the frequencies of genotypes among subgroups of MG patients, except for the difference between the 15 -50 year subgroup and control. Conclusion T allele of complement 3 gene rs7951 may be associated with the susceptibility of myasthenia gravis.