中文摘要：

背景与目的：EB病毒（Epstein-Barr virus,EBV）BamH Ⅰ-A右向转录物（BamH Ⅰ-A rightward transcripts,BARTs）可能与鼻咽癌的发生发展相关,而A73是BARTs家族的主要成员之一,该基因mRNA的表达水平在鼻咽癌组织中显著增高,提示A73参与鼻咽癌变过程。本研究旨在发现A73基因多态性及寻找与鼻咽癌易感性相关的多态性位点。方法：以从23例鼻咽癌组织和19例非鼻咽癌患者（鼻咽正常）的漱口水中提取的DNA为模板,巢式聚合酶链反应（polymerase chain reaction,PCR）扩增A73基因的所有外显子,直接测序并比对测序结果,寻找A73基因的多态性位点。随后在54例鼻咽癌成套标本（包括同一鼻咽癌患者的鼻咽癌组织、漱口水、外周血）和48例广东健康人的漱口水及51例健康人外周血中检测前面实验发现的高频变异点的分布情况,比较该位点在不同组织源性及鼻咽癌病例和健康对照之间的差异。所有测序序列均与B95.8细胞株序列比较。结果：在A73基因外显子区域共发现了3个多态性位点A157154C、G159188C、G159209C（与B95.8株序列比较）,其中A157154C呈现高频变异。在外周血中,鼻咽癌患者A157154C的比例（52/54,96.29%）显著高于广东健康人（33/51,64.70%,P〈0.001）。54例成套标本中13例该变异点的变化在同一鼻咽癌患者的鼻咽组织、漱口水和外周血中是不一致的。结论：A73基因A157154C的EBV亚型可能与鼻咽癌的发生发展相关。

英文摘要：

　BACKGROUND ＆ OBJECTIVE： A73 gene, one of the primary members in Epstein-Barr virus （EBV） BamHⅠ-A rightward transcripts （BARTs） family, is related to the development of nasopharyngeal carcinoma （NPC）. Its mRNA level is elevated in NPC tissues, suggesting that A73 participates in the carcinogenesis of NPC. This study was to explore the polymorphism loci of A73 gene and find its correlation to susceptibility to NPC. METHODS： Nested polymerase chain reaction （PCR） and direct sequencing were used to identify A73 gene polymorphisms in 23 specimens of NPC and 19 throat washing （TW） samples from non-NPC patients. The same methods were also used on additional 54 unitized NPC specimens [carcinoma tissue, matched TW sample and peripheral blood （PB） sample from the same patient], and 48 TW samples and 51 PB samples from healthy Cantonese to detect a polymorphism with high frequency found in previous step. Its distribution among different samples was compared. All sequences were compared with the sequence of B95.8 cells. RESULTS： Three polymorphisms A157154C, G159188C, and G159209C were identified in A73 gene. Among which, A157154C showed high frequency. The frequency of A157154C was significant higher in PB samples from NPC patients than in those from healthy Cantonese （96.29% vs. 64.70%, P〈0.001）. Among 54 unitized specimens, 13 cases showed discordances in different tissue origins. CONCLUSION： A157154C in A73 gene might be correlated to the occurrence and development of NPC.