Meta-analysis confirmed the significant elevation of placental Lep expression in PE placentas
To test the ability of placental Lep levels to differentiate non-PE from PE pregnancies, we performed a meta-analysis of gene expression profiles based on six PE placental studies (GSE4707, GSE10588, GSE24129, GSE25906, GSE44711, and GSE54618; see Table I). Among the 13,137 genes, Lep in PE placentas had the maximal change (1.9-fold) and the most significant difference (P < 0.0001) compared with non-PE placentas (Fig. 2 and Appendix 1). Furthermore, in each study, Lep levels were higher in PE compared with non-PE placentas (P< 0.05; Fig. 3). The overexpression of the Lep transcripts was found to be significant in all PE women (including early-onset, late-onset, and severe PE).