Duplication of large genomic regions during the evolution of vertebrate homeobox genes

The phylogenetic relationships of 21 murine Antp-class (Drosophila mutation Antennapedia-type class) homeobox genes have been analyzed, and several groups of related genes have been identified. The murine Antp-class homeobox genes are localized within four gene clusters. The similar structural organization of the four gene clusters strongly suggests that genes within a group of related Antp-class homeobox genes are derived from duplications of large genomic regions. After the duplication, the gross structures of the homeobox gene clusters have been maintained over a long period of evolutionary time, indicating that the specific organization of genes within a cluster may be of functional importance.