The most common molecular event in Beckwith–Wiedemann syndrome (BWS) is the biallelic expression of insulin-like growth factor 2 (IGF2) due to loss of imprinting (LOI), which is accompanied by methylation and/or silencing of the active maternal allele of H19 [77,78,79,80]. This evidence concerns the gene IGF2 and Beckwith-Wiedemann syndrome.