However, the KvDMR1 harbors two putative CTCF binding sites that may mediate non-coding RNA independent imprinting regulation [20], and the imprinting control center for Prader-Willi syndrome [21] also carries three CTCF binding sites (examined with a Search for CTCF DNA Binding Sites program, http://www.essex.ac.uk/bs/molonc/spa.html). Here, CTCF is linked to Prader-Willi syndrome.