Early Pregnancy Prediction of Spontaneous Preterm Birth Prior to 32 Completed Weeks of Pregnancy Using Plasma RNA: Transcriptome Discovery and Initial Validation of an RNA Panel of Markers.

Weiner, Carl P; Dong, Yafeng; Zhou, Helen; Cuckle, Howard; Ramsey, Risa; Egerman, Robert; Buhimschi, Irina; Buhimschi, Catalin

OBJECTIVE Compare the second trimester plasma cell-free (PCF) transcriptome of women who delivered at term to women with spontaneous preterm birth (sPTB)≦32weeks and identify/validate PCF ribonucleic acid (RNA) markers present by 16weeks. DESIGN Prospective case-control study. SETTING Academic tertiary care centre. POPULATION Pregnant women with known outcomes prospectively sampled. METHODS PCF RNA extracted from women at 22-24weeks (5 sPTB≦32weeks and 5 term) was hybridised to gene expression arrays. Differentially regulated RNAs for sPTB≦32weeks were initially selected based on p-value compared to control (p<0.01) and fold change (≥1.5x). Potential markers were then reordered by narrowness of distribution. Final marker selection was made by searching the Metacore™ database to determine whether the PCF RNA interacted with a reported set of myometrial Preterm Initiator genes. RNAs were confirmed by qRT-PCR and tested in a second group of 40 women (20 with sPTB ≦32weeks (mean gestation 26.5, standard deviation ±2.6weeks), 20 with spontaneous term delivery (40.1±0.9weeks) sampled 16-19+5weeks. MAIN OUTCOME MEASURE Identification of PCF RNAs predictive of sPTB≦32weeks. RESULTS 297 PCR RNAs were differentially expressed in sPTB≦32weeks. Further selection retained 99 RNAs (86 mRNAs and 13 miRs) and 5 of these interacted in silica with 7 Preterm Initiator genes. Four of 5 RNAs were confirmed and tested on the validation group. The expression of each confirmed PCF RNA was significantly higher in sPTB≦32weeks. In vitro study of the 4 mRNAs revealed higher expression in placenta of women with sPTB≦32weeks and the potential to interfere with myometrial quiescence. CONCLUSIONS The PCF RNA markers are highly associated with sPTB≦32weeks by 16weeks.