The Worst Potential Genetic Nightmare?

[Modem]

JG>I am writing a novel involving genetic engineering. What, in the
JG>opinion of readers of this newsgroup, would be the worst possible
JG>thing that could be engineered with this technology? 

JG>I am not an anti-genetics person, by the way, I'm just looking for a
JG>good "or else" scenario for my novel.

JG>What would it be? Making HIV airborne? Hybrid animals/humans? What
JG>would be the worst you could imagine?

JG>Thanks for your help.

JG>Jeff

Mass production of clones of "BARNEY".