BackgroundAbout 10 –15 % of all clinically recognized pregnancies result in spontaneous miscarriages, and chromosomal abnormalities are the most common reason. The conventional karyotyping on chorionic villus samples (CVSs) is limited by cell culture and its resolution. This study aimed at evaluating the efficiency of the application of high throughput genetic technology, including array comparative genomic hybridization (array CGH) and next generation sequencing (NGS) on the chromosomal copy number analysis of CVSs from early spontaneous miscarriages.ResultsFour hundred and thirty-six CVSs from early spontaneous abortion were collected. Genomic DNA was extracted using a routine method, and the chromosomal copy number variants (CNVs) were analyzed by array CGH and NGS. Two hundred and twenty-five samples (51.6 %) with abnormal chromosomes were identified among 436 samples, of which 188 samples (41.3 %) were aneuploidy, 23 samples (5.3 %) were segmental deletion and/or duplication cases, and 14 samples (3.2 %) were triploid. Two of the three cases with small segmental deletion and duplication were validated to be transferred from their fathers who were carriers of submicroscopic reciprocal translocation.ConclusionA high chromosomal abnormality detection rate on CVSs from early spontaneous miscarriage was achieved by array CGH and NGS. Specifically, the detection of submicroscopic recombination, which is sometimes missed by conventional karyotyping, was important for genetic counseling for the couples that suffered from recurrent miscarriages.

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.

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