Homeobox genes are a group of genes which contain a particular sequence of 180 bases called a homeobox. The homeobox is highly conserved in plants, animals and fungi and codes for some 60 amino-acids of the protein. The homeodomain can bind to DNA and switch genes on and off. Some people think that humans and mice had a common ancestor and subsequent mutations and evolution led to 2 different organisms.
Pax6 is a homeobox gene that causes blindness when mutated. The retina does not develop sufficiently in humans, mice and fruit flies.
Hox genes are homeobox genes only present in animals. They are found in gene clusters and are responsible for positioning body parts. Mammals have 4 clusters of 9-11 genes on different chromosomes. Humans have 39 Hox genes.