1.   Few, for instance, are found near the critical regions known as homeobox gene clusters.

2.   The two clusters evolved by duplication of an ancestral gene cluster before the divergence of the human and great ape lineages.

3.   These KOX ZNF gene clusters are, in turn, called cluster A and cluster B, respectively.

4.   Such gene clusters already have been discovered in other bacteria, including E. coli, which can be fatal to humans.