The rabibunny village is constantly harrased by mutants, for this reason, they offer Twinsen to open the door of the sacred carrot if he destroys the mutant factory. Twinsen then desables the factory by killing the green eggs that he finds there. From then on, the mutants are stopped being manufactured, but a lot of them still remain in the northern hemisphere. Twinen encounters some more mutants in Tipett Island.
There is no mention of mutants in LBA2.