@SeanNOLA: Although I agree that the exoframe was a pretty horrid idea, I think that the basic idea behind Fighting Chance was actually pretty good: nobody expected Cap to live so long (technically he should be about 80-90 years old right now) so it's likely that the Serum might have some unpredicted side-effects. Unfortunatly it was the 90s, so they had to stuff in some really crazy art.
The idea of the serum affecting his DNA is something that was added later. It was a little odd that he needed a complete blood transfusion when the serum was causing his body to shut down yet he got the transfusion from Red Skull in his cloned body. In order for the cloned body to have the Super Soldier Serum in it means it had to have affected his DNA.
Actually the transfusion from the Skull was to give Cap a dose of the "anti-serum" developed by Superia that reverted the degeneration started with Fighting Chance.