Reliable detection of subchromosomal deletions and duplications using cell-based noninvasive prenatal testing
Prenatal Diagnosis. 2018;38(13):1069-1078. DOI 10.1002/pd.5377. PMID 30357877. PMCID PMC6587831.
How to cite
AMA
Vossaert L, Wang Q, Salman R, Zhuo X, Qu C, Henke D, et al. Reliable detection of subchromosomal deletions and duplications using cell-based noninvasive prenatal testing. Prenat Diagn. 2018;38(13):1069-1078. doi:10.1002/pd.5377APA
Vossaert, L., Wang, Q., Salman, R., Zhuo, X., Qu, C., Henke, D., et al. (2018). Reliable detection of subchromosomal deletions and duplications using cell-based noninvasive prenatal testing. Prenatal Diagnosis, 38(13), 1069-1078. https://doi.org/10.1002/pd.5377BibTeX
@article{vossaert2018reliable,
title = {Reliable detection of subchromosomal deletions and duplications using cell-based noninvasive prenatal testing},
author = {Vossaert, Liesbeth and Wang, Qun and Salman, Roseen and Zhuo, Xinming and Qu, Chunjing and Henke, David and others},
journal = {Prenatal Diagnosis},
volume = {38},
number = {13},
pages = {1069-1078},
year = {2018},
doi = {10.1002/pd.5377},
pmid = {30357877}
}Standard prenatal screening reads cell-free DNA from a maternal blood draw, but that DNA is a mix of maternal and fetal fragments. It flags common whole-chromosome problems well, yet small deletions and duplications are harder to see and usually need an invasive follow-up test to confirm.
This group instead isolated whole fetal cells — trophoblasts — from about 30 mL of maternal blood, which yields pure fetal DNA. Across 125 samples they recovered on average 4.17 fetal cells each and sequenced them one cell at a time.
The single-cell data detected deletions and duplications from 1.2 to 18.9 Mb, every one matching the amniocentesis or chorionic villus result, and it separated two genotypes in a case of confined placental mosaicism.
Key findings
- Fetal cells were recovered from nearly every sample. Across 125 maternal blood samples the method found an average of 4.17 putative fetal trophoblasts per sample (0.18 cells/mL), enough to analyze as single cells.
- Single fetal cells resolved deletions and duplications down to the low-megabase range. Single-cell whole-genome amplification and low-coverage sequencing detected subchromosomal changes from 1.2 to 18.9 Mb, including an 18.9 Mb 4p (Wolf-Hirschhorn) deletion and a 1.2 Mb Xp gain.
- Every finding of 1 Mb or larger matched the invasive diagnostic result. For the four cases with abnormalities of at least 1 Mb, all copy-number calls were concordant with the microarray or karyotype data from amniocentesis or chorionic villus sampling.
CyteFinder in the methods
“After the depletion step, all nucleated cells were separated based on density centrifugation, fixed, and stained. All samples were spread on CyteSlides (RareCyte, 800 000 cells/well) and scanned on the CyteFinder instrument (RareCyte), as previously described.”
— Vossaert et al., Prenatal Diagnosis (2018), Methods, “Trophoblast enrichment and isolation”
Disclosure: RareCyte is listed as an author affiliation on the publication cited above.
Disclosure: RareCyte is named in the competing-interests statement of the publication cited above.
Why it matters for CyteFinder users
If your work turns on finding a few specific cells in a crowded background, this study shows the CyteFinder doing it in one of the harder settings there is. A fetal trophoblast is a single cell among the roughly 800,000 spread across a slide, and the instrument had to scan every well, read the cytokeratin and CD45 stains, and mark the cells worth picking. The rare-cell problem here is fetal rather than a tumor cell, but the demand on your instrument is the same: locate a scarce, specifically stained cell across a whole slide, then hand off clean coordinates for single-cell retrieval. What followed is the proof the detection held up — the picked cells yielded enough DNA for whole-genome amplification and sequencing, and calls down to 1.2 Mb agreed with the invasive diagnostic result. For CyteFinder users, the takeaway is that the scan-and-identify step you rely on for circulating tumor cells carries over to any rare cell you can stain, which widens where the instrument pays its way.
