PGF and preeclampsia: However, whether this imbalance impairs brain angiogenesis is unclear.21 Although genetic deletion of PlGF leads to impaired brain vascular development, including unilateral hypoplasia and less collateral vessel formation (ie, angiogenesis) in the circle of Willis, which initiates at the embryonic stage and persists after birth.14 At the same time, deletion of VEGF is lethal due to defects in the vasculature.22 In addition, less attention has been given to the VEGFR2 or the KDR (kinase insert domain-containing receptor) in preeclampsia.