Should pre-implantation genetic screening be implemented to routine clinical practice?

Abstract

The utilization of trophectoderm biopsy combined with comprehensive chromosome screening (CCS) tests for embryonic aneuploidy was recently suggested to improve IVF outcome, however, not without criticisms. Since mosaicism has been reported in as high as 90% of blastocyst-stage embryos, we aimed to evaluate the accuracy of trophectoderm multiple biopsies using next-generation sequencing (NGS). Eight top quality blastocysts underwent three trophectoderm biopsies each, followed by NGS. In four blastocysts, the rest of the embryo, which included the inner cell mass, was also analyzed. Five of the 24 (20.8%) trophectoderm biopsies revealed inconclusive results, while 4 (16.6%) demonstrated embryonic mosaicism. Overall, 10 (35.7%) of the 28 (24 trophectoderms and 4 inner cell masses) biopsies revealed mosaicism or inconclusive results. Our preliminary observations contribute to the ongoing discussion on the unrestricted clinical adoption of PGS, suggesting, that until proper evaluation of its effectiveness and cost-effectiveness will be provided, PGS should be offered only under study conditions, and with appropriate informed consents.

Chinese abstract

近来利用滋养外胚层活检和染色体筛查（CCS）检测非整倍体胚胎以提高体外受精的成功率，然而，并非没有质疑。由于囊胚阶段的镶嵌型已经高达90%，我们旨在使用新一代基因测序技术（NGS）评估多种滋养外胚层活检的准确性。八个高质量的胚泡每个都进行三次滋养外胚层活检，随后进行新型基因测序（NGS）。分析了四个囊胚阶段的胚胎以及其余的包括内细胞团的胚胎。24个滋养外胚层活检中的5个（20.8%）显示不确定的结果，而4个（16.6%）显示胚胎镶嵌现象。总的来说，28个（24个滋养外胚层和4内细胞团）中的10个（35.7%）活检显示镶嵌性或不确定的结果。我们的初步观察对正在进行关于是否在临床诊疗中常规应用PGS的讨论有帮助。表明除非充分评估其有效性和成本效益，否则PGS只有在研究，并且有知情同意的条件下进行。

• Aneuploidy
• mosaicism
• NGS
• PGS
• trophectoderm biopsy