目的　分析滑膜肉瘤t(X ;18)染色体易位断裂点基因组DNA序列特征 ,探讨其与滑膜肉瘤t(X ;18)染色体易位发生的关系。方法　采用长距离聚合酶链反应 (PCR)及DNA测序技术 ,对2例滑膜肉瘤新鲜标本t(X ;18)染色体易位断裂点基因组DNA序列进行了扩增及序列分析。结果　2例滑膜肉瘤标本均存在t(X ;18)染色体易位 ,分别导致SYT SSX1和SYT SSX2融合基因形成。DNA序列分析显示 ,SYT基因第 10内含子分别与SSX1和SSX2基因的第 4内含子发生融合。在 3种基因的断裂点附近均存在与共有易位素 (translin)识别序列高度同源的序列。还发现 3种基因的断裂点靠近 ,甚至位于呈回文结构的寡核苷酸序列中。SSX1和SSX2基因第 4内含子断裂点位于Alu重复序列附近 ,而SYT基因第 10内含子断裂点上游和下游各 5 0 0碱基内均未发现Alu或其他重复序列。在SYT两断裂点之间的DNA序列中存在一处拓扑异构酶Ⅱ的识别序列 ,但与两断裂点距离较远。结论　滑膜肉瘤染色体易位所涉及的 3种基因的基因组断裂点区域存在特征性的序列 ,可能与滑膜肉瘤染色体易位的发生有关 Objective To analyze the genomic DNA sequence of the chromosomal translocation breakpoint of synovial sarcoma t (X; 18), and to explore its relationship with the chromosomal translocation of synovial sarcoma t (X; 18). Methods Two genomic DNA sequences of the chromosomal translocation breakpoint of t (X; 18) in fresh specimens of synovial sarcoma were amplified and sequenced by long distance polymerase chain reaction (PCR) and DNA sequencing. Results T (X; 18) chromosomal translocations occurred in both synovial sarcoma specimens, resulting in the formation of SYT SSX1 and SYT SSX2 fusion genes, respectively. DNA sequence analysis showed that the tenth intron of SYT gene was fused with the fourth intron of SSX1 and SSX2 respectively. There are sequences highly homologous to the consensus translin recognition sequence near the breakpoints of the three genes. The three genes were also found to have breakpoints near, and even in, the oligonucleotide sequence in the palindrome. The breakpoint of intron 4 of SSX1 and SSX2 was located in the vicinity of Alu repeats, but no Alu or other repeats were found in all the 500 bases upstream and downstream of the tenth intron of SYT gene. There is a topoisomerase Ⅱ recognition sequence in the DNA sequence between the two breakpoints of SYT, but it is far away from the two breakpoints. Conclusions There are some characteristic sequences in the region of genomic rupture of the three genes involved in the chromosomal translocation of synovial sarcoma, which may be related to the occurrence of chromosomal translocations of synovial sarcoma