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Clinical Validation of a Prenatal Cell-Free DNA Screening Test for Fetal RHD in a Large U.S. Cohort
Marisa Gilstrop Thompson1, Wenbo Xu, Bridget Moore
1Delaware Center for Maternal Fetal Medicine, Newark, Delaware; and Natera, Inc., San Carlos, California.
Obstetrics and Gynecology
|November 26, 2024
Summary
A new noninvasive prenatal test accurately identifies fetal RHD status using cell-free DNA. This validated test aids in preventing RhD alloimmunization early in pregnancy.
Area of Science:
- Genetics
- Obstetrics
- Molecular Diagnostics
Background:
- RhD alloimmunization poses risks during pregnancy.
- Accurate fetal RhD genotyping is crucial for management.
- Noninvasive prenatal testing offers a safer alternative to invasive methods.
Purpose of the Study:
- To clinically validate a next-generation sequencing (NGS)-based noninvasive prenatal cell-free DNA (cfDNA) test for fetal RHD.
- To assess the accuracy and reliability of this cfDNA test in a large U.S. cohort.
Main Methods:
- A prospective clinical validation study involving 655 RhD-negative pregnant patients.
- Analysis of maternal cfDNA using NGS for fetal RHD genotyping.
- Comparison of cfDNA results with newborn serology and maternal RHD genotype.
Main Results:
- The cfDNA test demonstrated high accuracy for fetal RHD status.
- Sensitivity for RhD-positive fetuses was 100% (356/356).
- Specificity for RhD-negative fetuses was 99.3% (295/297), with accurate identification of RHD pseudogene.
Conclusions:
- This large U.S. validation confirms the accuracy of NGS-based cfDNA testing for fetal RHD.
- The test enables early and reliable noninvasive prenatal identification of fetal RHD genotype from 9 weeks gestation.
- This technology can significantly aid in preventing and managing RhD alloimmunization.
