Cell-Based NIPT Detects 47,XXY Genotype in a Twin Pregnancy

Abstract

Background: The existing risk of procedure-related miscarriage following invasive sampling for prenatal diagnosis is higher for twin pregnancies and some women are reluctant to test these typically difficultly obtained pregnancies invasively. Therefore, there is a need for noninvasive testing options that can test twin pregnancies at an early gestational age and ideally test the twins individually.Case presentation: A pregnant woman opted for cell-based NIPT at GA 10 + 5. As cell-based NIPT is not established for use in twins, the test was provided in a research setting only, when an ultrasound scan showed that she carried dichorionic twins.Materials and Methods: Fifty mL of peripheral blood was sampled, and circulating fetal cells were enriched and isolated. Individual cells were subject to whole-genome amplification and STR analysis. Three fetal cells were analyzed by chromosomal microarray (aCGH).Results: We identified 20 fetal cells all sharing the same genetic profile, which increased the likelihood of monozygotic twins. aCGH of three fetal cells showed the presence of two X chromosomes and a gain of chromosome Y. CVS from both placentae confirmed the sex chromosomal anomaly, 47,XXY and that both fetuses were affected.Conclusion: NIPT options can provide valuable genetic information to twin pregnancies that help the couples in their decision-making on prenatal testing. Little has been published about the use of cell-based NIPT in twin pregnancies, but the method may offer the possibility to obtain individual cell-based NIPT results in dizygotic twins.

Isolation of single circulating trophoblasts from maternal circulation for noninvasive fetal copy number variant profiling

“…The semi-automated methodology presented here for the isolation and single-cell analysis of cEVTS from maternal blood supports the feasibility and scalability of a cell-based noninvasive prenatal test for fetal genomic profiling down to ~1Mb in size. The goal of our work was to develop a new method that, different from others reported, [16][17][18][19] would (i) reduce hands-on manipulation of isolated fetal cells and (ii)…”

“…The semi‐automated methodology presented here for the isolation and single‐cell analysis of cEVTS from maternal blood supports the feasibility and scalability of a cell‐based noninvasive prenatal test for fetal genomic profiling down to ∼1Mb in size. The goal of our work was to develop a new method that, different from others reported, 16 , 17 , 18 , 19 would (i) reduce hands‐on manipulation of isolated fetal cells and (ii) both demonstrate the fetal origin by genetic confirmation (not only by immunophenotype) and perform fetal genome profiling for aneuploidy and subchromosomal variant in each isolated single cell. Current work is in progress to both validate our current workflow on a large patient cohort (over 1500 patients) to a single‐cell analytical LoD of ∼1Mb and to increase the overall number of samples with recovery and the number of cEVTs isolated per sample.…”

“…15,17,18 Recently, advances have been made in the single-cell sorting of cEVTs using flow cytometry, followed by Short-Tandem Repeats (STR) analysis. 19 However, fetal confirmation by STR analysis requires a separate additional test, which increases costs, hands-ontime and operator manipulation. In the context of a routine clinical testing application, manual protocols are not suitable or provide adequate reproducibility.…”

“…Recently, advances have been made in the single‐cell sorting of cEVTs using flow cytometry, followed by Short‐Tandem Repeats (STR) analysis. 19 However, fetal confirmation by STR analysis requires a separate additional test, which increases costs, hands‐on‐time and operator manipulation. In the context of a routine clinical testing application, manual protocols are not suitable or provide adequate reproducibility.…”

How does cell‐based non‐invasive prenatal test (NIPT) perform against chorionic villus sampling and cell‐free NIPT in detecting trisomies and copy number variations? A clinical study from Denmark

“…7 However, once isolated, every cell comes with the potential of an entire fetal genome uncontaminated by maternal DNA. Thus, they constitute an attractive source for non-invasive prenatal testing for aneuploidies, sex chromosome aberrations (SCA), and pathogenic CNVs, [8][9][10][11][12] as well as monogenic disorders. 13 For example, whole genome amplification from 3 harvested fetal cells rendered enough DNA for both chromosomal microarray (CMA) and cystic fibrosis screening.…”