Validation of multiple annealing and looping-based amplification cycle sequencing for 24-chromosome aneuploidy screening of cleavage-stage embryos

Abstract

Objective: To validate multiple annealing and looping-based amplification cycle (MALBAC) sequencing for 24-chromosome aneuploidy screening of cleavage embryos and to explore the chromosomal characteristics of embryos at the cleavage stage.

Design: The 24-chromosome aneuploidy analyses of the blastomeres included comparative genomic hybridization (CGH), single nucleotide polymorphism (SNP), and MALBAC sequencing.

Setting: University-affiliated IVF center.

Patient(s): Three couples who delivered babies from the same IVF cycle, which included 23 donated, frozen cleavage embryos.

Intervention(s): None.

Main outcome measure(s): Three blastomeres were selected from each single embryo and subject to CGH, SNP, and MALBAC sequencing for 24-chromosome aneuploidy, respectively. The results of MALBAC sequencing were compared with the results of CGH and SNP. The chromosomal status and occurrence of the abnormal chromosomes were investigated. The relationship between the embryos' morphology and the euploid state was analyzed.

Result(s): Among the 23 donated embryos, the MALBAC sequencing results of 18 (78.26%) embryos were identical to those of CGH or SNP, including 8 embryos that had identical results by all three techniques. In terms of euploidy, only 6 of these 23 embryos (26.09%) were diploid. Blastomere abnormality was observed in all autosomes and sex chromosomes. In addition, the frequency of abnormality was different for certain chromosomes.

Conclusion(s): With sequencing at 0.04× genome depth, MALBAC sequencing has been validated as a satisfactory method for 24-chromosome aneuploidy screening. The proportion of abnormal chromosomes was high in cleavage-stage embryos, and any chromosome could be abnormal.

Keywords: 24-chromosome aneuploidy screening; Cleavage embryo; comparative genomic hybridization (CGH); multiple annealing and looping-based amplification cycles (MALBAC); single nucleotide polymorphism (SNP).