Agilent Feature extraction software was used to collect original data from microarray followed by analysis with robust multichip average (RMA). Gene intensity data between PE group and control group were compared with t test after calibration with a stochastic variance model. Differentially expressed genes were identified from whole genomes. Independent-Samples T Test was used to compare mRNA levels in samples from PE patients and controls. Statistical tests were performed using SPSS 17.0, and p values <0.05 were considered significant. Before t test, test for equality of variances was performed, if variances were not equal, t test result would be corrected.