Prenatal detection of isochromosome 21 by QF-PCR. A comparison between FISH and traditional karyotyping.

Objective: To compare rapid aneuploidy diagnostic tests with traditional karyotyping in the prenatal detection of Down syndrome due to isochromosome 21.

Methods: Quantitative fluorescence PCR (QF-PCR) and fluorescent in situ hybridization (FISH) for chromosomes 13, 18, 21, X and Y were performed on uncultured amniotic fluid, followed by routine karyotyping. chromosomal and microsatellite analysis of peripheral blood from parents was also carried out.