There's good theoretical reason to think that. Evolution should eliminate diseases caused by self-defects, but arms races with pathogens can keep diseases around (either directly, caused by the pathogen, or indirectly, as a tradeoff due to things being selected for to resist the pathogens.)
If diseases caused by self defects arise mainly after reproducing (say in your 50s/60s/70s), would there be much evolutionary pressure to eliminate it?