AUTHOR=Li Lingping , Liu Xijing , Li Qinqin , Zhang Lili , Xiong Yueyue , Liu Shanling , Wang He , Zhu Hongmei , Zhang Xuemei 

TITLE=Case report: Prenatal diagnosis of rare chromosome mosaicism: discordant results between chorionic villi and amniotic fluid samples

JOURNAL=Frontiers in Genetics

VOLUME=Volume 14 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/genetics/articles/10.3389/fgene.2023.1165019

DOI=10.3389/fgene.2023.1165019

ISSN=1664-8021

ABSTRACT=Objective We described a special case of near-negative chromosome mosaicism in chorionic villi but complete monosomy X in amniotic fluid. 
Methods Chorionic villus sampling and amniocentesis were performed separately in the first and second trimesters. Chromosomal microarray (CMA) and rapid aneuploidy detection (QF-PCR and FISH) were performed on placental villi and uncultured amniotic fluid. After pregnancy termination, placenta, umbilical cord, and fetal muscle tissues were sampled for FISH detection.
Results The CMA revealed a lower signal from chromosome X in chorionic villi, with a copy number of 1.85, implying the presence of mosaic monosomy X. However, QF-PCR and FISH results were nearly normal. In uncultured amniotic fluid, CMA and rapid aneuploidy detection indicated complete monosomy X. Across different sampling points on the aborted fetus, FISH results varied from normal, to mosaic, and then complete monosomy X. 
Conclusion This case presents a rare and complex situation where sampling from uncultured chorionic villi indicated low-level chromosome mosaicism, but sampling from amniotic fluid revealed complete monosomy X. Although some of these discordant outcomes may be due to methodological limitations, we conclude that prenatal consultation should be combined with fetal ultrasound phenotype and genetic testing for a comprehensive evaluation of fetal genetic abnormalities.