Homeotic gene

Homeotic genes are homeobox genes that are responsible for segment identity in metazoan organisms. Inappropriate expression of homeotic genes will, in general, transform parts of the body into structures appropriate to other positions. An example would be the Antennapedia mutant of the fruit fly Drosophila, in which legs are found sprouting where antennae would normally be. Localized expression of homeotic genes is controlled by upstream maternal proteins, gap genes, and pair rule genes in the developmental cascade.

Homeotic genes are evolutionarily highly conserved and generally encode transcription factors involved in the fate of developing regions of the body. Groups of homeotic selector genes determine how different regions of an organism develop. Homeotic genes are often homologous between different species; these genes are present in essentially all animals, humans included.