Has transcriptional repression activity, partially through the recruitment of the corepressor TRIM28 but has also repression activity independently of this interaction. Essential during embryonic development, where it acts as direct repressor of a placental-specific transcript of IGF2 in early development and regulates convergent extension movements required for axis elongation and tissue morphogenesis in all germ layers. Also important for normal morphogenesis of extraembryonic tissues including the yolk sac, extraembryonic mesoderm and placenta. May enhance proliferation or maintenance of neural stem cells. Interacts with TRIM28. Isoform 3 is highly polymorphic with three major alleles: H, C1 and C1. The H allele is found at higher frequencies in Japanese (0.71) and Taiwan Chinese (0.72) populations compared to European (0.45) and African (0.39) populations. The H allele may be associated with smaller head size in infants. Belongs to the krueppel C2H2-type zinc-finger protein family. Truncated N-terminus. Contaminating sequence. Potential poly-A sequence.