A Microarray Approach for Systematic Identification of Placental-Derived RNA Markers in Maternal Plasma

Circulating fetal RNA in maternal plasma has offered a new approach for noninvasive prenatal diagnosis and monitoring. Circulating fetal RNA markers could potentially be used for all pregnant women without being limited by fetal–maternal genetic polymorphisms and fetal gender. Over the past few years, encouraging findings have been reported on the detection and possible clinical applications of circulating fetal RNA. Placental-derived RNA has been shown to be easily detectable in maternal plasma during pregnancy and rapidly cleared after delivery. Such observations suggest that the placenta is an important organ for releasing fetal RNA into maternal plasma. Noninvasive prenatal gene expression profiling of the placenta also has been demonstrated to be feasible by analyzing the circulating placental RNA in maternal plasma. Thus, circulating placental RNA is a potentially useful tool for noninvasive investigation of the placenta. Here, we describe a systematic method for efficient development of new placental-specific RNA markers that could be detected in maternal plasma. The method is based on the use of oligonucleotide microarray (Affymetrix, Santa Clara, CA) technology to simultaneously analyze >39,000 RNA transcripts in the placenta. This development has implication for the development of new markers\break for studying disease conditions associated with placental pathology, such as preeclampsia.