Fetal DNA in maternal plasma: progress through epigenetics.

The discovery of cell-free fetal DNA in maternal plasma has opened up new possibilities for noninvasive prenatal diagnosis. Most of the work in this field has focused on the detection of fetal genetic markers that are distinguishable from the background maternal DNA. The feasibility of detecting fetal epigenetic markers in maternal plasma using an imprinted locus was demonstrated in 2002. This work has recently led to the development of the first universal fetal epigenetic marker, hypomethylated maspin, which can be used for fetal DNA detection in maternal plasma, irrespective of fetal gender and genetic polymorphisms. It is expected that many more fetal epigenetic markers that can be used in this manner will be developed over the next few years. These markers may catalyze the eventual clinical use of circulating fetal DNA for noninvasive prenatal diagnosis, such as for the detection of fetal chromosomal aneuploidies.