Hemolytic disease of the fetus and newborn and fetal and neonatal alloimmune thrombocytopenia are caused by maternal antibodies against fetal alloantigens on red blood cells or platelets that are inherited from the father. After transplacental transport to the fetal circulation, antibodies of the IgG class may cause severe fetal anemia or bleeding complications. The indication for noninvasive fetal blood group genotyping is given if a clinically relevant antibody is detected in a pregnant woman and if the father is heterozygous (or unknown) for the implicated blood group allele. This mini-review will focus on the advantages and current limitations of next-generation sequencing (NGS) for noninvasive diagnosis of fetal blood groups which is, in contrast to fetal aneuploidy screening, proposed only by some research groups. Targeted massively parallel sequencing of short DNA fragments from maternal cell-free plasma samples enables counting of fetal alleles for many single nucleotide polymorphisms in parallel. This information can be utilized for estimation of the fetal fraction of cell-free DNA (cfDNA) as well as detection of the paternal blood group allele in question. Adherence to a cut-off of ≥4% fetal fraction for reporting conclusive results is recommended to avoid false-negative results due to low fetal fraction. For screening purposes of fetal RHD in RhD-negative pregnant women, real-time PCR methods are very well established. However, for diagnostic purposes, the targeted amplicon-based NGS approach has the inherent capability to estimate the fetal fraction of cfDNA. In the future, improving the accuracy of NGS by consensus sequencing of single cfDNA molecules may enable reliable fetal blood group genotyping already in the first trimester of pregnancy.

中文翻译：

---

下一代测序在无创胎儿分子血型基因分型中的潜力

胎儿和新生儿溶血性疾病以及胎儿和新生儿同种免疫性血小板减少症是由母体抗体对从父亲遗传的红细胞或血小板上的胎儿同种抗原的抗体引起的。经胎盘转运至胎儿循环后，IgG 类抗体可能导致严重的胎儿贫血或出血并发症。如果在孕妇中检测到临床相关抗体，并且父亲对相关血型等位基因是杂合的（或未知），则表明进行无创胎儿血型基因分型。这篇小型综述将重点介绍下一代测序 (NGS) 用于胎儿血型无创诊断的优势和当前局限性，与仅由某些研究小组提出的胎儿非整倍体筛查相反。来自母体无细胞血浆样本的短 DNA 片段的靶向大规模平行测序能够并行计算许多单核苷酸多态性的胎儿等位基因。该信息可用于估计无细胞 DNA (cfDNA) 的胎儿分数以及检测所讨论的父亲血型等位基因。建议遵守 ≥ 4% 胎儿分数的临界值来报告结论性结果，以避免由于胎儿分数低而导致假阴性结果。为了在 RhD 阴性孕妇中筛查胎儿 RHD，实时 PCR 方法非常成熟。然而，出于诊断目的，基于靶向扩增子的 NGS 方法具有估计 cfDNA 胎儿分数的固有能力。将来，