Validation of copy number variation sequencing for detecting chromosome imbalances in human preimplantation embryos

Chromosome aneuploidies commonly arise in embryos produced by assisted reproductive technologies and represent a major cause of implantation failure and miscarriage. Currently, preimplantation genetic diagnosis (PGD) is performed by array-based methods to identify euploid embryos for transfer to the patient. We speculated that a combination of next-generation sequencing technologies and sophisticated bioinformatics would deliver a more comprehensive and accurate methodology to improve the overall efficacy of embryo testing. To meet this challenge, we developed a high-resolution copy number variation (CNV) sequencing pipeline suitable for single-cell analysis. In validation studies, we showed that CNV-Seq was highly sensitive and specific for detection of euploidy, aneuploidy, and segmental imbalances in 24 whole genome amplification samples from PGD embryos that were originally diagnosed by gold standard array comparative genomic hybridization. In addition, CNV-Seq was capable of detecting, mapping, and accurately quantifying terminal chromosome imbalances down to 1 Mb in size originating from abnormal segregation of translocation chromosomes. These validation studies indicate that CNV-Seq displays the hallmarks of an accurate and reliable embryo test with the potential to further improve the overall efficacy of PGD.