Differential expansion and loss of C2H2-ZNF clusters in five mammalian genomes. A) Evolution of the C2H2-ZNF repertoires in primates, rodents and dog. The number of C2H2-ZNF clusters and the total number of C2H2-ZNF genes found in these clusters are mentioned on the species tree. Since Xenopus laevis and Gallus gallus C2H2-ZNF genes are used as an outgroup in phylogenetic studies, these species are also positioned on the tree. B) A graphical representation of different scenarios seen in the evolution of human C2H2-ZNF clusters and their syntenically homologous C2H2-ZNF clusters in chimpanzee, mouse, rat and dog. The human clusters selected and named on the graph as well as their syntenic counterparts were 1) present in all species, 2) primate-specific, 3) lost in rodents or 4) absent in dog. For each human C2H2-ZNF cluster named on the graph and described in Additional File 3, the first number indicates the chromosome number and the second is the number attributed to that cluster on the chromosome. Additional File 5 provides a more comprehensive graphical representation including the 40 human clusters that contain at least 3 C2H2-ZNF genes and their syntenic counterparts in the four other mammals.