应用短串联重复序列快速诊断21三体

目的　采用聚合酶链反应 -单链构象多态性技术 ,对短串联重复序列 (short tandem repeat,STR)进行分析 ,探讨应用串联重复序列信息进行 2 1三体定性诊断的可行性。方法　以染色体 G显带核型分析为对照 ,选择 19例 2 1三体阳性患儿和 3例高风险胎儿及其双亲为对象 ,抽提基因组 DNA,用聚合酶链反应扩增 D2 1S14 11和 D2 1S11位点的 STR片段 ,并对其进行单链构象多态性分析 ,通过电泳带型特征诊断 2 1三体。结果　本法可以通过检测三条染色体的 STR片段电泳带型来诊断 2 1三体。应用该基因诊断方法分析了 2 2例 2 1三体患儿 ,除 1例患儿的 D2 1S11电泳谱带与父母的电泳条带完全相同不能诊断外 ,其他病例的 D2 1S14 11和 D2 1S11位点的诊断结果与细胞遗传学核型分析结果相符 ,其中 3例孕中期高风险胎儿的分析结果被流产样品的核型分析所证实。结论　基于短串联重复序列的聚合酶链反应 -单链构象多态性分析技术是一种简单、快速和可靠的 2 1三体定性基因诊断技术 ,可应用于 2 1三体的基因诊断和遗传筛查。

Rapid molecular diagnosis of trisomy 21 using the PCR-STR-SSCP technique

Objective Developing a PCR-based method to diagnose trisomy 21 directly by alternative detection of the SSCP profiles of the STR fragments amplified. Methods The DNA samples from 19 trisomy 21 patients, 3 at-risk fetuses of trisomy 21 and a total of 44 samples from their parents as controls were drawn for this study, in which the trisomy 21 was determined by G-band karytyping. Two polymorphic STR at D21S11 and D21S1411 served as the gene markers, and two separate PCR-amplified primers were designed. The STR-amplicons denatured were subjected to polyacrylamide gel electrophoresis for SSCP analysis. Results This assay can identify three STR fragments representing parents' chromosome 21 by detecting the electrophoresis separation profiles of PCR-amplified fragments. With the use of this assay, the authors analyzed the 22 cases of trisomy 21;accurate diagnoses were made except for one case in which the electrophoresis pattern at D21S11 site could not present the diagnostic information because of the homozygous state of this family. The 3 at-risk fetuses were found to be the trisomy 21 patients, followed by confirmation of the results by G-band karytyping of aborted samples. Conclusion The present PCR-STR-SSCP assay can be applied as a simple, rapid and accurate method in the prenatal diagnosis and genetic screening of trisomy 21.