重症肌无力患者胸腺Fas基因突变及氨基酸变异分析

Study on Fas gene mutation and amino acid variation in thymus tissue of patients with myasthenia gravis

目的 :分析重症肌无力 (MG)患者胸腺Fas基因突变及其编码蛋白质的氨基酸变异 ,探讨Fas分子在重症肌无力发生中的作用。方法 :提取 8例MG患者胸腺总RNA ,经RT PCR法扩增出Fas基因全长 ,克隆后用荧光标记法进行基因测序 ,用DNASIS、OMIGA软件与Genbank中Fas序列进行同源性比较和分析。结果 :8例患者胸腺组织 6例出现Fas基因突变 ,突变率为 75 % (6 /8) ,其中 5例发生 2个以上位点突变 ,只有 1个位点突变的 1例 (1 2 .5 % ,1 /8) ;突变类型为 1 6 4位A→G ,相应的氨基酸变异为 5 5位Asp→Gly,96位His Arg,1 92位Arg→Lys和 2 5 1位Lys→Arg。Fas基因高度保守 ,患者之间同源性为 99.6 %～ 1 0 0 % ,Fas分子同源性为 98.7%～ 99.7%。结论 :重症肌无力患者胸腺组织中存在Fas基因突变和Fas分子结构变异 。

Aim: To study the functions of Fas molecule in myasthenia gravis by investigating whether Fas gene mutation and Fas molecule variation occur in thymus tissue of MG patients.Methods: The total RNA from thymus MG patients were extracted.The cDNA of Fas gene were amplified by reverse transcription polymerase chain reaction(RT PCR),the product was cloned into T Vectors and sequenced.DNASIS and OMIGA software were used for sequencing and homogenous analysis.Results: Most of MG patients thymus tissue had Fas gene mutation,and the mutation rate was 75%(6/8).Multi sites mutation rate was 62.5%(5/8).There were 4 point mutation forms:A→G at 164nt, A→G at 287nt, G→A at 575nt, and A→G at 752nt.Conclusion: Fas gene mutation exists in thymus tissues of MG patients.