There is a high incidence of chromosomal abnormalities in early human embryos, whether they are generated by natural conception or by assisted reproductive technologies (ART). Cells with chromosomal copy number deviations or chromosome structural rearrangements can compromise the viability of embryos; much of the naturally low human fecundity as well as low success rates of ART can be ascribed to these cytogenetic defects. Chromosomal anomalies are also responsible for a large proportion of miscarriages and congenital disorders. There is therefore tremendous value in methods that identify embryos containing chromosomal abnormalities before intrauterine transfer to a patient being treated for infertility—the goal being the exclusion of affected embryos in order to improve clinical outcomes. This is the rationale behind preimplantation genetic testing for aneuploidy (PGT-A) and structural rearrangements (-SR). Contemporary methods are capable of much more than detecting whole chromosome abnormalities (e.g., monosomy/trisomy). Technical enhancements and increased resolution and sensitivity permit the identification of chromosomal mosaicism (embryos containing a mix of normal and abnormal cells), as well as the detection of sub-chromosomal abnormalities such as segmental deletions and duplications. Earlier approaches to screening for chromosomal abnormalities yielded a binary result of normal versus abnormal, but the new refinements in the system call for new categories, each with specific clinical outcomes and nuances for clinical management. This review intends to give an overview of PGT-A and -SR, emphasizing recent advances and areas of active development.

中文翻译：

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染色体异常的胚胎植入前基因检测：非整倍性、嵌合和结构重排

早期人类胚胎的染色体异常发生率很高，无论它们是通过自然受孕还是通过辅助生殖技术 (ART) 产生的。具有染色体拷贝数偏差或染色体结构重排的细胞会损害胚胎的生存能力；人类自然生育能力低以及ART 的低成功率在很大程度上可归因于这些细胞遗传学缺陷。染色体异常也是导致大部分流产和先天性疾病的原因。因此，在宫内移植到接受不孕症治疗的患者之前识别含有染色体异常的胚胎的方法具有巨大的价值 - 目标是排除受影响的胚胎以改善临床结果。这是非整倍体 (PGT-A) 和结构重排 (-SR) 的植入前基因检测背后的基本原理。现代方法不仅能够检测整个染色体异常（例如，单体性/三体性）。技术改进和提高的分辨率和灵敏度允许识别染色体嵌合体（包含正常和异常细胞混合的胚胎），以及检测亚染色体异常，如节段缺失和重复。早期的染色体异常筛查方法产生了正常与异常的二元结果，但系统中的新改进需要新的类别，每个类别都有特定的临床结果和临床管理的细微差别。本综述旨在概述 PGT-A 和 -SR，