Parental mosaic trisomy 21 detected following maternal cell contamination of an amniotic fluid specimen from a normal male pregnancy

• Published in: Prenatal diagnosis Vol. 27; no. 9; pp. 858 - 860
• Main Authors: Street, Melissa L., Barber, John C. K., Boyle, Tracy A., Ellis, Katrina H., Bullman, Hilary, Homfray, Tessa
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01-09-2007; Wiley
• Subjects: Adult; Amniocentesis; Amniotic Fluid - cytology; Biological and medical sciences; Cells, Cultured; Down Syndrome - diagnosis; Down Syndrome - genetics; Female; Fundamental and applied biological sciences. Psychology; Genetics of eukaryotes. Biological and molecular evolution; Gynecology. Andrology. Obstetrics; Humans; Male; Management. Prenatal diagnosis; maternal cell contamination; Medical sciences; Molecular and cellular biology; Mosaicism; Mothers; Pregnancy; Pregnancy. Fetus. Placenta; prenatal diagnosis; trisomy 21; Chromosomal aberration; Amniocentesis; Trisomy; Parent; Prenatal Diagnosis; Gynecology; trisomy 21; Chromosome G21; Neonatology; Aneuploidy; Male; Down syndrome; Contamination; Pregnancy; Prenatal; Mother; Amniotic fluid; maternal cell contamination; Female; Genetics; Mosaicism; Cell
• ISSN: 0197-3851; 1097-0223
• DOI: 10.1002/pd.1782

We report a case of maternal mosaic trisomy 21 ascertained at prenatal diagnosis as a result of maternal cell contamination of an amniotic fluid sample. A 34 year old female was referred for karyotyping because of a previous trisomy 21 pregnancy. Chromosome analysis of primary in situ cultures showed a karyotype of 47,XX, + 21[6]/46,XY[32]/46,XX[2]. Molecular testing demonstrated maternal cell contamination of the amniotic fluid sample and G‐banded karyotyping of maternal blood showed that 3/200 cells had trisomy 21, consistent with the mother being a Down syndrome mosaic. A normal male baby with a 46,XY chromosome complement was delivered at 30 weeks. This case emphasises the need for close collaboration between cytogenetic and molecular genetics laboratories in resolving unusual cases of mosaicism. Copyright © 2007 John Wiley & Sons, Ltd.