Replication
A common characteristic of imprinted genes is asynchronous replication during the DNA synthesis phase of the mitotic cycle. The replication of two alleles of the same gene can differ according to which parent the allele originated from. On the human chromosome 11p15, the methylated paternal H19 allele replicates early in the S phase while the hypomethylated maternal allele replicates later. Studies by Bergstrom et al. have determined that the later-replicating maternal H19 allele is CTCF-bound, and that it is this CTCF binding that determines the time of H19 replication.
Read more about this topic: H19 (gene)