利用经宫颈不同部位的胎儿细胞进行产前诊断的初步研究

目的比较孕早期经宫颈不同部位获取的胎儿细胞量,以确定更佳的取材部位。方法收集孕5～10周人工流产妇女的经宫颈内口和宫颈外口冲洗液,分别称为内口冲洗组和外口冲洗组,每组各60例。提取冲洗液中的 DNA,对 Y 染色体的 SRY 基因进行扩增和定量。对人流后的绒毛采用直接法分析染色体核型确定流产胎儿性别。结果 (1)经宫颈内口冲洗组,实时定量 PCR 检测出71.4％(15/21)已知男胎的 SRY 基因,5.13％(2/39)已知女胎的 SRY 基因,总性别正确预测率为86.7％;经宫颈外口冲洗组,实时定量 PCR 检测出37％(10/27)已知男胎的 SRY 基因,6.25％(2/32)已知女胎的 SRY 基因,总性别正确预测率为67.8％。经宫颈内口冲洗组的总性别正确预测率和男胎阳性率均高于经宫颈外口冲洗组,差异有统计学意义(P<0.05)。(2)实时定量 PCR 检测经宫颈内口冲洗组 DNA 抽提液 SRY 基因的拷贝数为1487.2±430.5,高于经宫颈外口冲洗组702.4±365.7拷贝,差异有统计学意义(P<0.05)。结论经宫颈获取胎儿细胞为孕早期无创性产前诊断提供了一个可能途径,经宫颈内口水平能比外口得到更多的胎儿细胞,但应采取更加安全有效的取材方法。

Early prenatal diagnosis using fetal cells acquired from different sites of uterine cervix: a preliminary study

OBJECTIVE: To compare the presence of fetal cells in the transcervical lavage fluids obtained at different levels of uterine cervix so as to evaluate the better sampling place for early prenatal diagnosis. METHODS: Sixty samples of transcervical lavage fluid were obtained at the level of the internal orificium of cervix of 60 women during the 5 - 10th week of pregnancy who underwent artificial abortion (internal orificium group), and 60 samples of transcervical lavage fluid were obtained at the level of the external orificium of cervix of 60 women the same age during the 5 - 10th week of pregnancy who underwent artificial abortion too (external orificium group). Extraction and amplification of DNA were conducted by females to detect the presence of SRY gene of Y chromosome. The sex of the fetus was determined by chromosome karyotyping of the villi. RESULTS: (1) In the internal orificium group Y-derived sequences were detected in 71.4% (15/21) of the samples of known male pregnancy and 5.13% (2/39) cases of known female pregnancy, with a total correct sex prediction rate of 86.7%; In the external orificium group Y-derived sequences could be amplified in 37% (10/27) of the samples of known male pregnancy and 6.25% (2/32) of the samples of known female pregnancy, with a total correct sex prediction rate of 67.8%, significantly lower than that of the internal orificium group (P < 0.05). (2) The number of the copies of SRY gene of Y chromosome of the internal orificium group was 1487.17 +/- 430.45 copies, significantly higher than that of the external orificium group (702.41 +/- 365.71 copies, P < 0.05). CONCLUSION: Transcervical cell sampling provides a promising approach for early non-invasive prenatal diagnosis. More fetal cells can be acquired at the internal orificium level of cervix than at the external orificium level, however, more non-invasive and efficient sampling method should be taken.