Integrating Telomere Signals from PGT-A NGS Data: A Cost-Effective Approach to Optimize Embryo Selection

Authors:
Chi-Ying Lee*1, 2, En-Hui Cheng1, Hui-Hsin Shih1, 3, Han-Ni Tsai1, Yi-Pin Lin1, Chun-Chia Huang1, Chung-I Chen1, Wei-Che Lo1, Maw-Sheng Lee1, 3 ,4,
Affiliations:
Division of Infertility, Lee Women’s Hospital, Taichung, Taiwan.[1], Institute of Bioinformatics and Structural Biology, National Tsing Hua University, Hsinchu, Taiwan.[2], Institute of Medicine, Chung-Shan Medical University, Taichung, Taiwan.[3], Department of Obstetrics and Gynecology, Chung-Shan Medical University Hospital,Taichung, Taiwan.[4]

Study Question:

Can telomere measurement enhance embryo selection beyond morphology and PGT-A in ART?

Study Design, Size, Duration:

This IRB-approved study (Chung Shan Medical University Hospital, No. CS1-22094) reanalyzed PGT-A data from 3,550 blastocysts derived from 1,114 couples between September 2023 and August 2024 (mean maternal age: 36.5 years). Prior research has indicated that telomere length increases following fertilization. Given that PGT-A employs uniform but random sampling for sequencing to infer chromosomal ploidy based on read depth, we hypothesized that developmentally competent embryos with longer telomeres may have a higher likelihood of being represented in the sequencing reads. Thus, telomere length was approximated by calculating the frequency of telomeric sequence reads per million total reads, defined as the Teloscore. To ensure accurate evaluation of implantation outcomes, only single embryo transfer (SET) cycles were included, resulting in 259 cycles analyzed.

Materials, Setting, Methods:

In routine PGT-A, genomic DNA from trophectoderm biopsies was sequenced using the Embryomap platform, generating 36-bp single-end reads with a mean depth of approximately 1 million reads per embryo and a minimum quality score of Q ? 20. Telomeric reads were quantified and normalized to the total number of reads to generate the Teloscore. Statistical analyses included generalized estimating equations (GEE) and multivariable logistic regression to assess associations between Teloscore, embryo euploidy, and implantation outcomes. The average maternal and paternal ages were 35.5 and 38.9 years, respectively.
Main Results: Multivariable logistic regression identified Teloscore as the only significant predictor of implantation (OR = 1.106, 95% CI: 1.016–1.206, p = 0.020). A Day 5 biopsy showed borderline significance (p = 0.072). The predictive value of Teloscore persisted after adjustment for euploidy and clinical covariates. Technical reproducibility was confirmed through duplicate sequencing runs on the same samples, yielding a strong correlation between repeated Teloscore measurements (slope = 0.90, R2 = 0.77, p < 0.001). 

Conclusion:

Teloscore, derived from secondary analysis of standard PGT-A sequencing data, offers a cost-effective and biopsy-sparing metric for evaluating embryo viability. This novel biomarker may complement existing selection strategies and improve clinical decision-making in ART.