EPHX1 and preeclampsia: More recently, certain polymorphisms of the human mEH gene, EPHX1, have been associated with an increased risk to develop preeclampsia, a severe pregnancy complication, characterized by hypertension (Groten et al. 2014; Laasanen et al. 2002; Pinarbasi et al. 2007; Zusterzeel et al. 2001).