Rajcan-Separovic Evica
Department of Pathology and Laboratory Medicine, University of British Columbia and, Child and Family Research Institute, 950 West 28th, Vancouver BC, Canada.
Eur J Med Genet. 2020 Feb;63(2):103644. doi: 10.1016/j.ejmg.2019.04.001. Epub 2019 Apr 13.
Next generation sequencing (NGS) has revolutionized the diagnosis of postnatal genetic diseases, but so far has been used less frequently to study reproductive disorders. Here we provide an overview of approaches and outcomes of genome sequencing for identifying causes of recurrent pregnancy loss (RPL). This includes exome sequencing to look for pathogenic sequence changes in the whole exome or in a preselected list of genes considered important for early embryonic development and pregnancy maintenance, as well as low coverage whole genome sequencing useful for identifying cryptic balanced chromosome rearrangements and copy number variants (CNVs) in couples with RPL and miscarriages. For the purpose of this review only studies with at least 2 pregnancy losses were included with NGS performed on complete families, or only on miscarriages, couples or females with RPL. Overall, mutations in candidate genes responsible for recurrent embryonic/fetal loss were found in up to 60% of cases, opening the door for possible identification of affected future pregnancies at the preimplantation stage. Recurrence of specific mutations or affected genes in different studies was rare (e.g.DYNC2H1, KIF14, RYR1 and GLE1) however genes involved in cell division, cilia function or fetal movement were frequently identified as candidates, the later possibly reflecting the fact that a large number of studied cases had features of fetal akinesia deformation sequence (FADS). Genome sequencing of the couple and miscarriages is most informative, as it allows analysis of the individual mutations as well as their collective burden on the genome and biological processes. However genome sequencing of the couple with RPL with follow up of candidate parental mutations in miscarriages appears to be a promising avenue when miscarriage DNA amounts or quality are suboptimal for whole genome studies. In the future, increasing the number of studied families, establishment of a database cataloguing CNVs and mutations found in early pregnancy loss as well as their functional assessment in miscarriage cells and parental reproductive tissues is needed for improved understanding of their role in adverse pregnancy outcome.
新一代测序（NGS）彻底改变了产后遗传疾病的诊断方式，但迄今为止在生殖障碍研究中的应用频率较低。在这里，我们概述了用于确定复发性流产（RPL）原因的基因组测序方法和结果。这包括外显子组测序，以寻找整个外显子组或在被认为对早期胚胎发育和妊娠维持重要的预选基因列表中的致病序列变化，以及低覆盖度全基因组测序，这对于识别RPL夫妇和流产夫妇中的隐匿性平衡染色体重排和拷贝数变异（CNV）很有用。出于本综述的目的，仅纳入了至少有2次流产的研究，这些研究对完整家庭进行了NGS检测，或仅对流产组织、RPL夫妇或女性进行了检测。总体而言，在高达60%的病例中发现了导致反复胚胎/胎儿丢失的候选基因中的突变，这为在植入前阶段可能识别受影响的未来妊娠打开了大门。不同研究中特定突变或受影响基因的复发很少见（例如DYNC2H1、KIF14、RYR1和GLE1），然而参与细胞分裂、纤毛功能或胎儿运动的基因经常被确定为候选基因，后者可能反映了大量研究病例具有胎儿运动障碍变形序列（FADS）特征这一事实。对夫妇和流产组织进行基因组测序信息最为丰富，因为它允许分析个体突变以及它们对基因组和生物过程的总体负担。然而，当流产DNA的数量或质量不足以进行全基因组研究时，对有RPL的夫妇进行基因组测序并对流产组织中的候选亲本突变进行随访似乎是一条有前途的途径。未来，需要增加研究家庭的数量，建立一个数据库，对早期妊娠丢失中发现的CNV和突变进行编目，并对流产细胞和亲本生殖组织进行功能评估，以更好地理解它们在不良妊娠结局中的作用。
