Beckwith-Wiedemann syndrome (BWS, OMIM 130650), either sporadic (>85%) or familial (<15%), is caused by mutation or deletion of imprinted genes CDKN1C, H19 and LIT1 as well as by hypermethylation in the H19/IGF2-imprinting control region within the chromosome 11p15.5 region [1]. The gene discussed is KCNQ1OT1; the disease is Beckwith-Wiedemann syndrome.