Our gene of the month is Antennapedia, which literally means “antenna feet”. As you might have guessed from the name, fruit flies with a faulty version of Antennapedia have an extra pair of legs growing out of their head, where their antenna should be. It’s a type of gene known as a homeotic gene, responsible for controlling the overall organisation of body parts like the limbs, wings, head and so on. While fruit flies have just 8 of these crucial genes, mammals have four clusters of related genes, known as HOX genes, with each cluster containing up to 11 genes.
And although mistakes in human HOX genes don’t lead to legs growing out of our heads, faults in the genes are responsible for major developmental defects, showing that these crucial genes share common jobs across the whole animal kingdom.