1. Screening for Fetal Aneuploidy and Sex Chromosomal Anomalies in a Pregnant Woman With Mosaicism for Turner Syndrome—Applications and Advantages of Cell-Based NIPT
- Author
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Line Dahl Jeppesen, Lotte Hatt, Ripudaman Singh, Palle Schelde, Lotte Andreasen, Sara Markholt, Dorte L. Lildballe, and Ida Vogel
- Subjects
cell-based noninvasive prenatal testing ,sex chromosomal aneuploidies ,turner mosaic ,non-invasive prenatal testing ,extravillous trophoblast ,Genetics ,QH426-470 - Abstract
Background: Cell-free NIPT and cell-based NIPT are risk-free testing options using maternal blood samples to screen for fetal aneuploidies, but the methods differ. For cell-free NIPT, the fetal fraction of cell-free DNA in plasma is analyzed with a high background of maternal DNA. In contrast, for cell-based NIPT, a limited number of the rare, intact fetal cells are isolated for the genetic analysis. This case demonstrates the differences regarding testing for fetal sex-chromosomes anomalies (SCAs) between these two tests.Materials and Methods: A pregnant woman with mosaicism for Turner syndrome opted for NIPT in first trimester. For the cell-free NIPT analysis, DNA extraction, genome-wide massive parallel sequencing, and data analysis were carried out as described by the kit manufacturer (Illumina©, San Diego, CA, USA). For cell-based NIPT, the first sample gave no result, but the woman consented to repeat cell-based NIPT. After whole genome amplification and STR analysis, fetal DNA from three individual fetal cells was subjected to chromosomal microarray (aCGH, Agilent oligoarray, 180 kb).Results: Fetal fraction was 7%, and cell-free NIPT showed 2 copies of chromosomes 13, 18, and 21 and a decreased proportion of chromosome X, suggestive of fetal Turner syndrome. In contrast, the cell-based NIPT result showed no aneuploidy and two X-chromosomes in the fetus.Conclusion: cell-based NIPT may provide a non-invasive testing option to screen for SCAs in women with mosaicism for monosomy-X in blood, where cell-free NIPT cannot discriminate whether the X-loss is maternal or fetal.
- Published
- 2021
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