The human gene encodes a protein containing one KRAB domain and eleven zf-C2H2 domains. Domain order of chimpanzee homologous gene, orangutan homologous gene and gibbon orthologous gene resembles human gene, while rhesus homologous gene differs. We could not infer the ancestral state. Either gain of sequences in rhesus lineage or loss of sequences in the common ancestral lineage of human, chimpanzee, orangutan and gibbon could be an explanation.