孕妇血浆胎儿DNA检测及其在产前诊断中的应用

目的检测孕妇血浆中游离胎儿DNA的水平，探讨应用孕妇血浆胎儿DNA进行非损伤性产前基因诊断的可行性。方法应用血浆DNA抽提法提取63例孕7～40周妇女血浆中胎儿DNA，运用PCR扩增技术对SRY基因和4个短串联重复序列（STR）多态位点（D21S11、D21S1411、D21S1412、D21S1414）进行检测。结果在33例妊娠男胎的孕妇血浆中，有29例出现SRY基因扩增带，孕早、中、晚期的SRY基因检出率分别是72．7％（8／11）、90．9％（10／11）、100％（11／11）。用4个单一STR多态位点检测出胎儿特异等位基因的比例分别为51／63、49／63、16／63、48／63。联合应用4个多态位点可以确定所有孕妇血浆中的胎儿DNA。结论在不同的妊娠阶段都可检测到孕妇血浆中的胎儿DNA，胎儿DNA检出率随孕周的增加增高。孕妇血浆中游离胎儿DNA可以用于无创伤产前诊断。

DETECTION OF FETAL DNA IN MATERNAL PLASMA AND ITS APPLICATION IN PRENATAL DIAGNOSIS

ObjectiveTo detect the regularity of appearance and disappearance of free fetal DNA in plasma of pregnant women and to explore the possibility of noninvasive prenatal gene diagnosis by using fetal DNA in maternal plasma.Methods The DNA templates were extracted by plasma DNA extraction from 63 gravida(conceived 6-40 weeks) plasma.SRY gene and four short tandem repeats(STRs)(D21S11,D21S1411,D21S1412,D21S1414) of fetal DNA were detected by polymerase chain reaction(PCR).ResultsSRY gene was detected in 29 of 33 male-bearing pregnant-women plasma.The detecting rates of SRY gene were 72.7%(8/11),90.9%(10/11) and 100%(11/11) at early pregnancy,medium-term pregnancy,and late pregnancy,respectively.The detecting rates of a fetal-specific band were 51/63,49/63,16/63,and 48/63 by means of four single STRs analysis,respectively.The fetal DNA in plasma was identified in all pregnant women by combining with four STRs analysis.ConclusionFetal DNA in maternal plasma can be detected in different gestational stages.The detection rates of fetal DNA in maternal plasma increase with the week of gestation.Fetal DNA in maternal plasma could be regarded as the gene resource for noninvasive prenatal diagnosis.