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Updated: Mar 28, 2026
Microsatellite DNA Genotyping and Flow Cytometry Ploidy Analyses of Formalin-fixed Paraffin-embedded Hydatidiform Molar Tissues
Published on: October 20, 2019
[Misdiagnosis of mosaic tetrasomy 9p in a fetus by single nucleotide polymorphism-based array]
Jianzhu Wu1, Yingjun Xie, Baojiang Chen
1Fetal Medicine Center, Department of Gynecology and Obstetrics, the First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510080, P.R. China. wujianzhu3140@126.com.
Objective:
To explore the reason for discordant results of karyotyping and microarray analysis in a fetus with mosaic tetrasomy 9p.
Methods:
Amniocentesis was carried out for a pregnant woman with advanced age for whom ultrasound scan has indicated fetal ventricular expansion, intrauterine growth retardation and persistent upper venous cavity. G-banded karyotyping and single nucleotide polymorphism-based arrays (SNP-array) analysis were performed at the same time.
Results:
Analysis of amniocytic chromosome has suggested mosaic tetrasomy 9p (47,XX,+psu idic(9)(q21)[23]/46,XX[27]). While SNP-array has detected a non-mosaic trisomy 9p with a 68.7 Mb duplication at 9p24.3q21.11. The results of the two methods were therefore discordant.
Conclusion:
SNP-array will analyze genetic material in the form of numbers rather than morphology. For chimeras containing two types of cell lines, when the mosaic rate was close to 50% and the average amount of genetic material of the chimeras was equivalent to the amount of genetic material of non-chimeras, microarray analysis may come to the conclusion of a non-mosaic heteroploidy. Therefore, microarray results for large segment chromosome abnormalities should be combined with the results of G-banded karyotyping for genetic counseling.
