Distribution Patterns of Segmental Aneuploidies in Human Blastocysts Identified by Next-generation Sequencing

Objective: To evaluate the ability of next-generation sequencing (NGS) to detect pure and mosaic segmental aneuploidies in trophectoderm biopsies and to identify distribution patterns in whole blastocysts.

Design: Validation study.

Setting: Reference laboratory.

Patient(s): Seventy couples with known karyotypes who had undergone preimplantation genetic screening with diagnoses at the blastocyst stage using array comparative genomic hybridization (aCGH).

Intervention(s): None.

Main Outcome Measure(s): Concordance rates for segmental and whole-chromosome aneuploidies determined between aCGH and NGS, and estimates of mosaicism levels of segmental aneuploidies in fixed blastocysts.

Result(s): We used NGS with amplified DNA from trophectoderm biopsies in which segmental aneuploidies had been previously detected by array comparative genomic hybridization (aCGH). Single-cell fluorescent in situ hybridization (FISH) was then used as an independent form of analysis. The concordance rate between NGS and aCGH was 124 (98.4%) of 126 for the detection of segmental aneuploidies, and 48 (96.0%) of 50 for whole-chromosome aneuploidies. The overall concordance rate was 99.8% (2,276 of 2,280 chromosomes assessed). After FISH analyses with 41.4 ± 24.3 cells per blastocyst, 26 (92.9%) of 28 segmentals detected by aCGH and NGS were confirmed. The FISH analysis did not detect the segmentals in two blastocysts, in which all cells analyzed were euploid.

Conclusion(s): This is the first report analyzing distribution patterns of segmental aneuploidies in trophectoderm biopsy by NGS. We have demonstrated that NGS allows the detection of pure and mosaic segmental aneuploidies with the same efficiency as aCGH. The FISH analysis confirmed the existence of these events in the trophectoderm and the inner cell mass.