Lo Y M, Hjelm N M, Fidler C, Sargent I L, Murphy M F, Chamberlain P F, Poon P M, Redman C W, Wainscoat J S
Department of Chemical Pathology, Chinese University of Hong Kong, Prince of Wales Hospital.
N Engl J Med. 1998 Dec 10;339(24):1734-8. doi: 10.1056/NEJM199812103392402.
The ability to determine fetal RhD Status noninvasively is useful in the treatment of RhD-sensitized pregnant women whose partners are heterozygous for the RhD gene. The recent demonstration of fetal DNA in maternal plasma raises the possibility that fetal RhD genotyping may be possible with the use of maternal plasma.
We studied 57 RhD-negative pregnant women and their singleton fetuses. DNA extracted from maternal plasma was analyzed for the RhD gene with a fluorescence-based polymerase-chain-reaction (PCR) test sensitive enough to detect the RhD gene in a single cell. Fetal RhD status was determined directly by serologic analysis of cord blood or PCR analysis of amniotic fluid.
Among the 57 RhD-negative women, 12 were in their first trimester of pregnancy, 30 were in their second trimester, and 15 were in their third trimester. Thirty-nine fetuses were RhD-positive, and 18 were RhD-negative. In the samples obtained from women in their second or third trimester of pregnancy, the results of RhD PCR analysis of maternal plasma DNA were completely concordant with the results of serologic analysis. Among the maternal plasma samples collected in the first trimester, 2 contained no RhD DNA, but the fetuses were RhD-positive; the results in the other 10 samples were concordant (7 were RhD-positive, and 3 RhD-negative).
Noninvasive fetal RhD genotyping can be performed rapidly and reliably with the use of maternal plasma beginning in the second trimester of pregnancy.
无创确定胎儿RhD状态的能力对于治疗伴侣为RhD基因杂合子的RhD致敏孕妇很有用。近期在母血中发现胎儿DNA，这增加了利用母血进行胎儿RhD基因分型的可能性。
我们研究了57名RhD阴性孕妇及其单胎胎儿。用基于荧光的聚合酶链反应（PCR）检测分析从母血中提取的DNA中的RhD基因，该检测灵敏度足以在单个细胞中检测到RhD基因。通过脐血血清学分析或羊水PCR分析直接确定胎儿RhD状态。
在57名RhD阴性女性中，12名处于妊娠早期，30名处于妊娠中期，15名处于妊娠晚期。39名胎儿为RhD阳性，18名胎儿为RhD阴性。在妊娠中期或晚期女性的样本中，母血DNA的RhD PCR分析结果与血清学分析结果完全一致。在妊娠早期采集的母血样本中，2份不含RhD DNA，但胎儿为RhD阳性；其他10份样本结果一致（7份为RhD阳性，3份为RhD阴性）。
从妊娠中期开始，利用母血可快速、可靠地进行无创胎儿RhD基因分型。
