Several panelists thought that the cancer signal may have reflected an ascertainment bias, and, further, that a young homozygous FH population would be less susceptible to an elevated cancer risk.

FORBES: FDA Panel Recommends Approval Of Mipomersen For Familial Hypercholesterolemia

"There is only a proportion of the animal population here that is susceptible to the disease, but it is not entirely clear how much of the animal collection would have to be culled should the outbreak reach Edinburgh Zoo, " he said.

BBC: Zoo reopens after disease scare

And in the segments of the population that are most susceptible to the extreme effects of the flu -- like the elderly, who make up the majority of the cases of flu-related deaths -- the vaccinations are even less effective.

CNN: Flu vaccine attitudes abroad differ from U.S.

Other genes, that either kill the malaria parasite or make the flies susceptible to insecticides, can be tagged onto the modified genes, and will also spread through the population.

BBC: GM mosquito bid to tackle malaria