Division of Therapeutic Immunology and Transfusion Medicine, Karolinska Institutet, Solna, Sweden.
Department of Women's Health, Division of Obstetrics, Karolinska University Hospital, Stockholm, Sweden.
Vox Sang. 2022 Nov;117(11):1296-1301. doi: 10.1111/vox.13348. Epub 2022 Sep 14.
Anti-D prophylaxis, administered to RhD-negative women, has significantly reduced the incidence of RhD immunization. Non-invasive fetal RHD screening has been used in Stockholm for more than 10 years to identify women who will benefit from prophylaxis. The method is based on a single-exon approach and is used in early pregnancy. The aim of this study was to update the performance of the method.
The single exon assay from Devyser AB is a multiplex kit detecting both exon 4 of the RHD gene and the housekeeping gene GAPDH. Cell-free DNA was extracted from 1 ml of plasma from EDTA blood taken during early pregnancy, weeks 10-12. The genetic RHD results were compared with serological typing of newborns for a determination of sensitivity and specificity.
In total, 4337 pregnancies were included in the study; 44 samples (1%) were inconclusive either due to maternal RHD gene variants (n = 34) or technical reasons (n = 10). Of the remaining 4293 pregnancies, a total number of nine discrepant results were found. False positive results (n = 7) were mainly (n = 4) due to RHD gene variants in the child. False-negative results were found in two cases, of which one was caused by a technical error. None of the false-negative cases was due to RHD gene variants. Overall, the sensitivity of the method was 99.93% and specificity 99.56%.
The single-exon assay used in this study is correlated with high sensitivity and specificity.
抗-D 预防疗法已广泛应用于 RhD 阴性女性，这显著降低了 RhD 免疫的发生率。非侵入性胎儿 RHD 筛查已在斯德哥尔摩使用超过 10 年，以确定哪些女性将受益于预防疗法。该方法基于单外显子方法，用于早期妊娠。本研究旨在更新该方法的性能。
Devyser AB 的单外显子检测法是一种多重试剂盒，可同时检测 RHD 基因的第 4 外显子和管家基因 GAPDH。从 EDTA 采血管采集的 1ml 血浆中提取无细胞 DNA，妊娠 10-12 周。将遗传 RHD 结果与新生儿的血清学分型进行比较，以确定敏感性和特异性。
本研究共纳入 4337 例妊娠；由于母体 RHD 基因突变（n=34）或技术原因（n=10），44 例（1%）样本结果不确定。在剩余的 4293 例妊娠中，共发现 9 例不一致的结果。假阳性结果（n=7）主要是由于婴儿的 RHD 基因突变（n=4）所致。假阴性结果发现于两例，其中一例是由于技术错误。无一例假阴性结果是由于 RHD 基因突变所致。总的来说，该方法的敏感性为 99.93%，特异性为 99.56%。
本研究中使用的单外显子检测法具有较高的敏感性和特异性。
