What is "hox gene"

n. (context genetics English) Any of the genes in the vertebrate homeobox

Hox genes (a subset of homeotic genes) are a group of related genes that control the body plan of an embryo along the cranio-caudal (head-tail) axis. After the embryonic segments have formed, the Hox proteins determine the type of segment structures (e.g. legs, antennae, and wings in fruit flies or the different types of vertebrae in humans) that will form on a given segment. Hox proteins thus confer segmental identity, but do not form the actual segments themselves.

An analogy for the Hox genes can be made to the role of a play director that calls which scene the actors should carry out next. If the play director calls the scenes in the wrong order, the overall play will be presented in the wrong order. Similarly, mutations in the Hox genes can result in body parts and limbs in the wrong place along the body. Like a play director, the Hox genes do not act in the play or participate in limb formation themselves.

Hox genes are defined as having the following properties:

• Their protein product is a transcription factor
• They contain a DNA sequence known as the homeobox
• In many animals, the organization of the Hox genes in the chromosome is the same as the order of their expression along the anterior-posterior axis of the developing animal, and are thus said to display colinearity.