The phylogenetic tree of the FGFR genes closely resembles that of the vertebrate TACC1-3 genes. Recently, detailed analyses of the chromosomal regions containing the FGFR gene family in humans, mouse and the arthopod D. melanogaster have revealed the conservation of paralogous chromosomal segments between these organisms (Fig. 2, [13], Table 1 [see Additional file 1]). This has provided further support that an ancient chromosomal segment was duplicated twice during vertebrate evolution, with the first duplication that gave rise to the human chromosome 4p16/5q32-ter and human chromosome 8p/10q23-ter ancestors occurring in the early stages after the invertebrate divergence. This suggests that the ancestral FGFR-TACC gene pair most probably arose prior to the initial duplication and subsequent divergence of these paralogous chromosomal segments, estimated to have occurred 687 ± 155.7 MYA. This has raised the suggestion that a fourth TACC gene in vertebrates would reside in the same chromosomal region as FGFR4. Indeed this hypothesis has been used in support for the RHAMM gene as a member of the TACC family [10]. Human RHAMM maps to chromosome 5q32 in a region bounded by GPX3 and NKX2E. These loci separate two clusters of genes on human chromosome 5 that are paralogous with 4p16. Interestingly, these three clusters are located on different chromosomes in mouse and rat (Fig. 2), further suggesting that this cluster of genes was transposed into this region after the primate/rodent divergence.