HOX genes play a fundamental role in the development of the vertebrate central nervous system, axial skeleton, limbs, gut, urogenital tract and external genitalia, but it is only in the last 4 years that mutations in two of the 39 human HOX genes have been shown to cause congenital malformations; HOXD13, which is …

Mutations in homeotic genes cause displaced body parts (homeosis), such as antennae growing at the posterior of the fly instead of at the head. Mutations that lead to development of ectopic structures are usually lethal.

HOX genes are a family of regulatory genes that encode transcription factors and are essential during embryonic development. These genes are highly conserved between species such that all metazoans possess a common genetic system for embryonic patterning.

The HOX genes are partly responsible for determining the anterior–posterior axis in the developing embryo and regulate the formation of musculoskeletal structures in each body segment.

In vertebrates, specifically humans and mice, there are a total of 39 Hox genes organized into 4 distinct clusters.

In other words, mutations occur randomly with respect to whether their effects are useful. Thus, beneficial DNA changes do not happen more often simply because an organism could benefit from them.

Secondary Clustering. The Hox gene cluster has been a major focus in evolutionary developmental biology. This is because of its key role in patterning animal development and widespread examples of changes in Hox genes being linked to the evolution of animal body plans and morphologies.

Each little piece of a living thing, known as a cell, has DNA in it. In humans each of these cells have 2 copies of the DNA, but in strawberries each of these have 8 copies of the DNA (scientists call this octoploid). That means strawberries have 4 times as many copies of DNA as humans, making it 4 times easier to see!