Transgenic overexpression of the paternally expressed Igf2 gene increased fetal growth (Sun et al., 1997), and upregulation or downregulation of IGF2 via aberrant imprinting is associated with the overgrowth disorder Beckwith-Wiedemann syndrome and the growth retardation disorder Silver-Russell syndrome, respectively (Jacob et al., 2013). Here, IGF2 is linked to Beckwith-Wiedemann syndrome.