Discordant structural chromosomal aberrations in chorionic villi and amniotic fluid leading to a formation of an isochromosome 21: a case report.

We propose a multiple-step mechanism as a possible theoretical explanation for the formation of these discordant structural chromosomal aberrations in the chorionic villi and amniotic fluid. With this case report, we want to highlight the importance of understanding the possible underlying embryological mechanisms when interpreting results from different prenatal analyses.