"Hox genes are clusters of “master switches” in the genome that act like body-plan architects. .webp)
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Each gene produces a protein that turns other genes on or off, telling cells where they are along the head-to-tail axis.
Strikingly, the order of Hox genes on the chromosome matches the order of the body parts they control — a phenomenon called colinearity.
In mammals there are four clusters (Hox A–D), conserved across animals from flies to humans.
Even small shifts in their regulation can make the difference between a fin, a limb, or a digit."
CEH