instead of getting to choose your mutations or rolling on a table, you must apparently own a certain card to have that ability.
As I read elsewhere:
Player: “OK, so here’s my Gamma World character. His mutations are Kinetic Bolt, Precognition, and Anti-Necrobiosis.”
DM: “Anti-Necrobiosis? Cool! So you are collecting the boosters now?”
Player: “Uh, actually my buddy just told me about the mutation and I wrote down the details. But you can check it with your DDI subscription.”
DM: “Sorry, go out and buy a few boosters if you really want that mutation.”
Player: (mumbles and starts thinking about Mutant Future.)