2017年1月21日

Day 3胚胎高達50-80%胚胎呈現染色體鑲嵌化mosaicism
Day 5胚胎剩5-10%胚胎呈現染色體鑲嵌化mosaicism
Day 5胚胎染色體正常只占52%, 染色體不正常只占43%, 染色體鑲嵌化占6%

Summary of data from relevant CCS studies on the cytogenetic constitution of ICM and TE samples from disaggregated human blastocysts. No sign of preferential allocation or confinement of chromosomally abnormal cells to the TE or ICM lineage was observed. The fact that results were almost identical for samples from the TE and ICM indicates that data obtained from a sample of a few cells biopsied from the blastocyst TE can generally be considered representative of the ICM chromosomal complement. Data taken from Northrop et al. (2010), Fragouli et al. (2008), Johnson et al. (2010) and Capalbo et al. (2014).

Summary of data from relevant CCS studies on the cytogenetic constitution of ICM and TE samples from disaggregated human blastocysts. No sign of preferential allocation or confinement of chromosomally abnormal cells to the TE or ICM lineage was observed. The fact that results were almost identical for samples from the TE and ICM indicates that data obtained from a sample of a few cells biopsied from the blastocyst TE can generally be considered representative of the ICM chromosomal complement. Data taken fromNorthrop et al. (2010), Fragouli et al. (2008), Johnson et al. (2010) and Capalbo et al. (2014).

http://humrep.oxfordjournals.org/content/early/2016/10/13/humrep.dew250.long

 2016 Oct 13. [Epub ahead of print]

Detecting mosaicism in trophectoderm biopsies: current challenges and future possibilities.

Capalbo A1, Ubaldi FM2, Rienzi L2, Scott R3, Treff N3.

Abstract

Embryonic mosaicism, defined as the presence of karyotypically distinct cell lines within an embryo, has been frequently reported with a high incidence in preimplantation embryos derived from IVF and is thought to be one of the major biological limitations for the routine application of PGD for aneuploidies (PGD-A). The incidence of mosaicism in preimplantation embryos is in fact reported to be between 4 and 90%. However, these data are in sharp contrast with what is known from clinical pregnancies, where true foetal mosaicism is observed in less than 0.5% of cases. Here, we challenge these previous observations in preimplantation embryos, presenting an alternative perspective, which also considers the impact of technical variation to diagnose mosaicism as one possible cause contributing to overestimation of the incidence of mosaicism in embryos. Although euploid/aneuploid mosaicism may be present in blastocysts, the possibility of detecting this phenomenon within a single trophectoderm biopsy represents a contemporary challenge to bring about improvement to the practice of PGD-A. The purpose of this opinion paper is to provide a critical review of the literature, provide a possible alternative interpretation of the data, and discuss future challenges with diagnosing mosaicism in PGD-A cycles.

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