Abstract

Objective: To validate a semiconductor next-generation sequencing (NGS)–based method to detect unbalanced chromosome translocation in preimplantation embryos. Methods: The study consisted of a blinded retrospective evaluation with NGS of 145 whole genome amplification products obtained from biopsy of cleavage-stage embryos or blastocysts, derived from 33 couples carrying different balanced translocations. Consistency of NGS-based copy number assignments was evaluated and compared with the results obtained by array-comparative genome hybridization (array-CGH). Results: 162 segmental imbalances derived from 33 different chromosomal translocations were reliably identified with the NGS-based protocol, with the smallest detectable chromosomal segment being 5Mb in size. Of the 145 embryos analysed, 20(13.8%) resulted balanced, 43(29.6%) were unbalanced, 53(36.5%) were unbalanced and aneuploid, and 29(20%) resulted balanced but aneuploid. NGS sensitivity for unbalanced/aneuploid chromosomal call (consistency of chromosome copy number assignment) was 99.75%(402/403), with a specificity of 100%(3077/3077). NGS specificity and sensitivity for unbalanced/aneuploid embryo call were 100%. Conclusions: NGS can detect chromosome imbalances in embryos with the added benefit of simultaneous comprehensive aneuploidy screening. Given the high level of consistency with array-CGH, NGS has been demonstrated a robust high-throughput technique ready for clinical application in preimplantation genetic diagnosis for chromosomal translocations, with potential advantages of automation, increased throughput and reduced cost.