Transcription regulator required to maintain maternal and paternal gene imprinting, a process by which gene expression is restricted in a parent of origin-specific manner by epigenetic modification of genomic DNA and chromatin, including DNA methylation. Acts by controlling DNA methylation during the earliest multicellular stages of development at multiple imprinting control regions (ICRs) (PubMed:30602440). Acts together with ZFP57, but seems to be the major factor in human early embryonic imprinting maintenance. In contrast, in mice, ZFP57 plays the predominant role in imprinting maintenance (PubMed:30602440). Binds various differentially methylated regions (DMR). Expressed in the oocyte, expression is maintained at least until blastocyst stage. Belongs to the krueppel C2H2-type zinc-finger protein family.