Newly evolved rodent-specific genes from the mature phase represent three distinct gene families. Among preferentially expressed genes, the mature cluster is highly enriched for genes that have evolved since rodents diverged from primates. Of the 37 rodent specific genes identified by either Homologene or Ensembl (see blue gene names), 29 are called rodent specific by both Homologene and Ensembl, two by Homologene only (*), and six by Ensembl only (**). Three large gene families account for a majority of the rodent-specific genes: the prolactin-like protein family, the CEA-related cellular adhesion molecule, and pregnancy-specific glycoprotein family, and the cathepsin family.
