CDKN1C and Beckwith-Wiedemann syndrome: Because 11p15 is a paradigmatic imprinted region, because 11p15 imprinting abnormalities are associated with beta cell proliferation in the focal variant of congenital hyperinsulinism (FoCHI) and the Beckwith–Wiedemann Syndrome (BWS)31–34, and because insulinomas display marked reductions in the cell cycle inhibitor, p57KIP2 encoded by CDKN1C in the 11p15 imprinted region (see below), we performed deep CpG methylome sequencing in the 11p15.5-p15.4 region on 10 insulinomas and compared this to the methylation pattern in two sets of FACS-sorted normal human beta cell preparations (Fig. 4b–h).