In the current work, we hypothesized that the onset of hypertensive disorders in pregnancy may be associated with missing KIR ligands defined as the absence of one or more fetal HLA epitopes for the corresponding KIRs in the mother (MSLs), but also with the mismatches (incompatibilities) between KIR gene polymorphism in mothers and the HLA types in fetuses (23). Here, KIR3DL1 is linked to hypertensive disorder.