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Updated: Dec 20, 2025
Pre-Implantation Genetic Testing for Aneuploidy on a Semiconductor Based Next-Generation Sequencing Platform
Published on: August 17, 2022
[Improvement of algorithm based on free DNA fragment size for non-invasive prenatal test]
Li Zhang1, Qian Zhu, Shanling Liu
1Department of Obstetrics and Gynecology, Chengdu Integrated Traditional Chinese and Western Medicine Hospital, Chengdu First People's Hospital, Chengdu, Sichuan 610071, China. wanghe_cd@126.com.
Objective:
To derive more sensitive and accurate Z-scores for noninvasive prenatal testing of fetal trisomies based on a combined DNA count- and size- algorithm.
Methods:
One hundred eighty women at a high risk for fetal aneuploidies underwent amniocentesis. An effective cut-off value for DNA size ratio was explored. Conventional count-based Z-scores and size ratio-corrected Z scores were calculated. The reliability of each Z-score was assessed through comparison with the results of cytogenetic analysis.
Results:
With the cut-off value set as 150 bp, the ratio of small DNA is positively correlated with the proportion of fetal DNA. The sensitivity and specificity of conventional count-based Z-scores were 75.00%, and 98.86%, respectively. This rate has increased to nearly 100% with a count-based 150 bp size correction.
Conclusion:
Compared with count-based methods alone, count-based Z-scores with 150 bp size correction may better predict fetal trisomies.
