Preimplantation genetic testing and carrier status detection in patients with balanced chromosomal rearrangements: a real-world multicenter retrospective study

Abstract

Objective: To investigate the euploid rate of blastocysts in couples with balanced chromosomal rearrangements and to evaluate the accuracy of the mapping allele with resolved carrier status (MaReCs) technique in discriminating between non-carrier and carrier embryos.

Design: Multicenter, retrospective, cohort study.

Subjects: We involved 2,002 couples with various types of balanced chromosomal rearrangements (reciprocal translocations, Robertsonian translocations, and inversions), who underwent in vitro fertilization treatment between January 2017 and September 2023.

Exposure: Blastocyst euploidy was assessed using preimplantation genetic testing for structural rearrangements, and the carrier status of euploid embryos was determined using MaReCs. For the transferred euploid embryos, amniocentesis was performed at 16-20 weeks of gestation to examine fetal chromosomes. The amniocentesis results were used as the gold standard to evaluate the accuracy of the MaReCs technique.

Main outcome measures: The euploid rate of blastocysts in couples with balanced chromosomal rearrangements and the accuracy of the MaReCs technique.

Results: In total, 13,730 embryos from 2,629 preimplantation genetic testing for structural rearrangement cycles among 2,002 couples were analyzed. Approximately 64.3% (1,287/2,002) of couples obtained euploid embryos in the first controlled ovarian hyperstimulation cycle and the percentage was 63.5% (1,670/2,629) of all cycles. The total euploid rate of blastocysts was 24.2% (3,324/13,730). Three hundred thirty-two couples in 360 cycles requested to distinguish the euploid embryos. A total of 1,021 blastocysts were discriminated, in which 49.4% (505/1,021) were non-carrier. 78.3% of patients (260/332) obtained non-carrier embryos in the first controlled ovarian hyperstimulation cycle. Follow-up data showed that among the 122 patients undergoing amniocentesis, the consistency between MaReCs and amniocentesis was 99.2% (121/122).

Conclusion: Mapping allele with resolved carrier status is a simple and precise method for distinguishing the carrier status of euploid embryos, providing a reliable solution for patients with balanced chromosomal rearrangements to stop the passing on of chromosome rearrangement to the next generation.

Keywords: Balanced chromosome rearrangement; euploid; mapping allele with resolved carrier status (MaReCs); preimplantation genetic testing for structural rearrangements (PGT-SR).