Hospital Universitario Central de Asturias, Servicio de Bioquímica, Oviedo, Spain.
Clin Chem Lab Med. 2010 Aug;48(8):1121-6. doi: 10.1515/CCLM.2010.234.
Hemolytic disease of the fetus and newborn (HDN) is caused primarily by feto-maternal RhD incompatibility. Although all RhD negative pregnant women undergo routine antenatal RhD prophylaxis at 28 weeks of gestation, and following delivery if the newborn is RhD positive, HDN has not been eradicated. Here, we investigated fetal Rhesus D (RHD) genotype in maternal plasma during the first trimester of pregnancy in our area.
Plasma samples were obtained from 111 RhD negative pregnant women, between 9 and 13 weeks of gestation. DNA from maternal plasma containing cell-free fetal DNA (cffDNA) was analyzed by quantitative PCR (qPCR) to detect RHD exons 5 and 7. A beta-globin (HBB) sequence was quantified to estimate total DNA concentration. qPCR results were compared with newborn RhD determined in cord blood serum. The influence of several gestational parameters on DNA concentration was also analyzed.
The specificity and sensitivity of the assay was 93% and 100%, respectively, with 97% diagnostic accuracy. Cell-free DNA concentrations during the first trimester of pregnancy were not affected by the gestational parameters studied (free-beta fraction of human chorionic gonadotropin and pregnancy-associated plasma protein A concentrations, fetal sex, materno-fetal ABO blood group incompatibility, maternal weight and gestational age).
Non-invasive fetal RHD genotyping during the first trimester of pregnancy can be determined with a high specificity, thus representing a valuable tool for improving the management of RhD negative pregnant women. As a high percentage of pregnant women participate in the routine first trimester combined screening program for aneuploidies, the fetal RHD study could be of immediate implementation, since the same blood collection could be used.
胎儿和新生儿溶血病（HDN）主要由母婴 RhD 不合引起。尽管所有 RhD 阴性孕妇在妊娠 28 周时都接受常规产前 RhD 预防措施，如果新生儿为 RhD 阳性，则在分娩后也会接受预防措施，但 HDN 尚未被根除。在这里，我们研究了本地区孕妇妊娠早期母体外周血胎儿 RhD（RHD）基因型。
采集 111 例 RhD 阴性孕妇妊娠 9-13 周的外周血血浆样本。采用定量 PCR（qPCR）法分析含有游离胎儿 DNA（cffDNA）的母体外周血 DNA，以检测 RHD 外显子 5 和 7。用β珠蛋白（HBB）序列定量来估计总 DNA 浓度。qPCR 结果与新生儿脐血血清中 RhD 进行比较。还分析了几个妊娠参数对 DNA 浓度的影响。
该检测方法的特异性和敏感性分别为 93%和 100%，诊断准确率为 97%。妊娠早期母体外周血游离 DNA 浓度不受所研究的妊娠参数（人绒毛膜促性腺激素游离-β亚基和妊娠相关血浆蛋白 A 浓度、胎儿性别、母胎 ABO 血型不合、孕妇体重和妊娠年龄）的影响。
妊娠早期非侵入性胎儿 RHD 基因分型具有较高的特异性，因此是改善 RhD 阴性孕妇管理的有价值工具。由于大多数孕妇都参与了常规定期的唐氏综合征筛查，因此可以立即实施胎儿 RHD 研究，因为可以使用相同的血液采集。
