The unmethylated paternal allele permits transcription of the antisense transcript KCNQ1OT1 (also known as LIT1) and silencing of genes including KCNQ1 and CDKN1C. Maternal methylation at the KvDMR1 is thought to prevent transcription of the KCNQ1OT1 gene and enable expression of CDKN1C. Loss of methylation (LOM) at the KvDMR1 is seen in up to 50% of sporadic BWS and is associated with biallelic expression (loss of imprinting) of KCNQ1OT1 and silencing of maternal CDKN1C expression [7]–[9]. Here, KCNQ1OT1 is linked to Beckwith-Wiedemann syndrome.