Real-time quantitative PCR for the detection of fetal aneuploidies

In prenatal analysis, one of the major concerns is the detection of fetal aneuploidies. Several molecular methods have been described recently for the rapid analysis of amniotic fluid and chorionic villi. Fluorescence in situ hybridization (FISH) and polymerase chain reaction (PCR) of short tandem repeats are already implemented in prenatal laboratories and permit the evaluation of the major chromosomal aberrations within 24 h. However, both methods have their disadvantages. The advent of real-time PCR has revolutionized the measurement of nucleic acid copy numbers in recent years. Quantitative PCR, a term that was only 10 years ago considered to be an oxymoron, is now widely accepted. We demonstrated previously the feasibility of detection of trisomy 21 by real-time PCR, and here we describe the modified test that permits simultaneous analysis of trisomies 18 and 21. This approach has been demonstrated in a recent large-scale analysis, and it is presented in detail in this chapter.