If a single mutation turns off the growth of some pair of legs within an organism, what's most likely affected?

If a single mutation turns off the growth of some pair of legs within an organism, the most affected is the growth of the legs of an organism. This means that during DNA replication, the mutation that has happened has been replicated and inhibits the growth that is responsible for the growth of the legs.

A single mutation that turns of the growth of the pair of legs for an organism means that most likely the Hox genes have been affected. The Hox genes are responsible for the formation of the posterior portion of the body.