Luizon et al. (2012) evaluated whether epistatic interactions among seven clinically relevant SNPs of eNOS (T-786C, rs2070744, a VNTR in intron 4, and Glu298Asp, rs1799983), MMP-9 [C-1562T, rs3918242 and −90(CA)13-25, rs2234681] and VEGF (C-2578A, rs699947, and G-634C, rs2010963) could be associated with PE or gestational hypertension. This evidence concerns the gene MMP9 and preeclampsia.