Noninvasive single-cell-based prenatal genetic testing: A proof of concept clinical study
Prenatal Diagnosis. 2024;44(3):304-316. DOI 10.1002/pd.6529.
How to cite
AMA
Bellair M, Amaral E, Ouren M, Roark C, Kim J, O'Connor A, et al. Noninvasive single-cell-based prenatal genetic testing: A proof of concept clinical study. Prenat Diagn. 2024;44(3):304-316. doi:10.1002/pd.6529APA
Bellair, M., Amaral, E., Ouren, M., Roark, C., Kim, J., O'Connor, A., et al. (2024). Noninvasive single-cell-based prenatal genetic testing: A proof of concept clinical study. Prenatal Diagnosis, 44(3), 304-316. https://doi.org/10.1002/pd.6529BibTeX
@article{bellair2024noninvasive,
title = {Noninvasive single-cell-based prenatal genetic testing: A proof of concept clinical study},
author = {Bellair, M. and Amaral, E. and Ouren, M. and Roark, C. and Kim, J. and O'Connor, A. and others},
journal = {Prenatal Diagnosis},
volume = {44},
number = {3},
pages = {304--316},
year = {2024},
doi = {10.1002/pd.6529}
}Prenatal genetic testing forces a trade-off. Amniocentesis and chorionic villus sampling are diagnostic but invasive, carrying a small risk of pregnancy loss; cell-free DNA screening is risk-free but resolves fewer of the small deletions and duplications that can matter clinically. Fetal cells that circulate in a mother's blood offer a third path — a whole, intact fetal genome to read without an invasive procedure — but they are vanishingly rare.
This proof-of-concept clinical study evaluated a cell-based test that recovers single fetal trophoblasts from a maternal blood draw and reads each cell's genome by whole-genome sequencing. Across 401 pregnancies, the single-cell approach detected aneuploidy and subchromosomal changes and agreed with invasive testing wherever the two were compared.
Key findings
- The single-cell test agreed with invasive diagnosis across a follow-up cohort. Among 243 pregnancies scheduled for chorionic villus sampling or amniocentesis, results for singleton pregnancies agreed with the invasive standard apart from 10 cases attributable to placental mosaicism.
- The assay resolved subchromosomal changes, not just whole-chromosome aneuploidy. Beyond trisomies, it detected deletions and duplications down to 1.5 Mb and 2 Mb, including a 6.3 Mb 15q11.2-q13 Prader-Willi/Angelman deletion and a 1.407 Mb Williams syndrome deletion at 7q11.23.
- Reading pure single cells gave concordant calls within each case. Because every analyzed cell is a single fetal trophoblast, all 210 high-quality cells across 74 multi-cell cases agreed on the presence or absence of pathogenic copy-number changes.
CyteFinder in the methods
“Cells with the highest CK staining intensity were collected and the enriched cell fraction was loaded into CyteSlides (RareCyte, Seattle, WA) with DAPI and subjected to automated cell scanning using a CyteFinder/CytePicker (RareCyte). Candidate cells were reviewed in a gallery (Figure S1), and presumptive fetal trophoblasts were manually picked into microfuge tubes using a micromanipulator within the CytePicker.”
— Bellair et al., Prenatal Diagnosis (2024), Methods, “Protocol”
Why it matters for CyteFinder users
If you are weighing CyteFinder for rare-cell work, look at the step it carried in this study. The whole test depends on finding a handful of fetal trophoblasts among the millions of maternal blood cells around them, and then reading each one's genome — which is only possible if you can first locate those rare cells on a slide and confirm which ones are worth picking. That is the job the instrument did here: after the enriched cell fraction was deposited onto CyteSlides, CyteFinder scanned the whole slide automatically and imaged the candidate cytokeratin-positive, CD45-negative cells so they could be reviewed in a gallery and retrieved one at a time. Two things follow for your own workflow. Because the scan images every candidate before anything is picked, you decide which cells go forward rather than trusting an upstream enrichment step to have kept the right ones. And because each retrieved cell is a single, pure fetal cell, its copy-number profile can be read on its own and checked against the other cells from the same case — the per-cell control that let this study resolve a change as small as a 1.5 Mb deletion.
