Prenatal Detection of Chromosome Aneuploidy by Quantitative Fluorescence PCR

Autosomal chromosome aneuploid pregnancies that survive to term, namely, trisomies 13, 18, and 21, account for 89% of chromosome abnormalities with a severe phenotype identified in prenatal samples. They are traditionally detected by full karyotype analysis of cultured cells. The average reporting time for a prenatal karyotype analysis is approximately 14 days, and in recent years, there has been increasing demand for more rapid prenatal results with respect to the common chromosome aneuploidies, to relieve maternal anxiety and facilitate options in pregnancy. The rapid tests that have been developed negate the requirement for cultured cells, instead directly testing cells from the amniotic fluid or chorionic villus sample, with the aim of generating results within 48 h of sample receipt. Interphase fluorescence in situ hybridization is the method of choice in some genetic laboratories, usually because the expertise and equipment are readily available. However, a quantitative fluorescence (QF)-PCR-based approach is now widely used and reported as a clinical diagnostic service in many studies. It may be used as a stand-alone test or as an adjunct test to full karyotype or array CGH analysis, which scan for other chromosome abnormalities not detected by the QF-PCR assay.