The overall goal of the proposed project is to understand the biology of feto-maternal cell-free DNA and RNA trafficking, and to use the knowledge gained to develop novel prenatal diagnostic applications. The overall hypothesis to be tested is that cell-free fetal DNA and mRNA in the maternal circulation and amniotic fluid originates from specific fetal tissue sources and contains unique fetal gene sequences that can be used for prenatal diagnosis of genetic and developmental disorders. Evidence thus far indicates that significant amounts of cell-free DNA, and to a lesser degree, RNA, circulate within the serum and plasma of pregnant women. These nucleic acids have a short half-life and are cleared within hours of delivery of the fetus or newborn. There is also a significant amount of cell-free fetal DNA and RNA present in the amniotic fluid. Currently, little is known about the tissue of origin of these nucleic acid sequences and how they are produced.
Specific aim 1 of the project is to use cell-free fetal DNA in maternal plasma, archived serum samples, and amniotic fluid supernatants as sources of clinical material to develop new clinical tests that could improve existing noninvasive assays to determine the risk of fetal aneuploidy or single gene disorders such as congenital adrenal hyperplasia (CAH). To date clinical applications have focused on detection and quantitation of uniquely fetal sequences as an indication of pregnancy complications. A major limitation has been that many of these analyses have been limited to male fetuses, which carry a Y chromosome. Thus, specific aim 2 is to use uniquely fetal mRNA gene sequences for the identification and quantitation of fetal nucleic acids in maternal plasma, independent of fetal gender. We will examine if increased or decreased gene expression, as measured by circulating mRNA sequences in maternal blood, can be used to noninvasively detect fetal aneuploidy or other complications of pregnancy.
In aim 3 we will determine the tissue of origin of the circulating nucleic acids by amplifying specific genes of hematopoietic, placental, and fetal origin. We will also use cell-free mRNA present in amniotic fluid to examine gene expression via microarrays. We will examine differences between fetuses due to gestational age and different pathologies. ? ?
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