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Updated: Jun 22, 2025
Semiconductor Sequencing for Preimplantation Genetic Testing for Aneuploidy
Published on: August 25, 2019
Assessing the necessity of screening ≤5 Mb segmental aneuploidy in routine PGT for aneuploidies
Jiaqi Zhang1, Meng Qin1, Mochen Ma1
1Center for Reproductive Medicine, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China.; National Clinical Research Center for Obstetrics and Gynecology, Beijing, China.; Key Laboratory of Assisted Reproduction (Peking University), Ministry of Education, Beijing, China.; Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproductive Technology, Beijing, China.
Research Question:
Does routine clinical practice require an increase in the resolution of preimplantation genetic testing for aneuploidies (PGT-A) to detect segmental aneuploidies ≤5 Mb?
Design:
This retrospective study analysed 963 trophectoderm biopsies from 346 couples undergoing PGT between 2019 and 2023. Segmental aneuploidies ≥1 Mb were reported. The characteristics, clinical interpretation and concordance of segmental aneuploidies ≤5 Mb were analysed.
Results:
The incidence of segmental aneuploidies was 15.1% (145/963) in blastocysts, with segmental aneuploidies of ≤5 Mb accounting for 2.3% (22/963). The size of the segmental aneuploidies showed a skewed distribution. Segmental aneuploidies ≤5 Mb were found to occur more frequently on the q arm of the chromosome, compared with the p arm. Losses of ≤5 Mb segmental aneuploidies were more prevalent than gains, with 17 deletions compared with 5 duplications. Of the segmental aneuploidies, 63.6% (14/22) ≤5 Mb were de novo, and 50.0% (7/14) of de-novo segmental aneuploidies were pathogenic/likely pathogenic (P/LP) copy number variations, accounting for 0.7% of 963 blastocysts. For blastocysts carrying ≤5 Mb segmental aneuploidies, a re-analysis of back-up biopsy samples showed that 35.7% of de-novo segmental aneuploidies (5/14) were not detected in the back-up samples. Cases were reported in which prenatal diagnosis (amniocentesis) revealed the absence of embryonic ≤5 Mb segmental aneuploidies detected at the blastocyst stage.
Conclusions:
The incidence of P/LP de-novo ≤5 Mb segmental aneuploidies in human blastocysts is extremely low. There is no compelling need to increase the resolution of PGT-A to 5 Mb in routine clinical practice.
