IGF2 and Silver-Russell syndrome: Moreover, placenta obtained from imprinting growth syndrome patients with disrupted IGF2 signaling are often associated with placentomegaly in BWS cases, due to hypervascularization and hyperplasia (Aoki et al., 2011; Armes et al., 2012), but also small hypoplastic placentas in SRS cases (Yamazawa et al., 2008), showing striking similarities to our mouse studies.