Methylation at mouse Cdkn1c is acquired during postimplantation development and functions to maintain imprinted expression.

Monoallelic expression of imprinted genes is generally associated with differential methylation. Methylation may be inherited as the gametic imprinting mark or may be acquired postfertilization. Here, we characterize a differentially methylated region associated with the mouse Cdkn1c gene and find that it is confined to a CpG island that begins 600 bp 5' of the promoter and extends into the transcription unit.