How do genetic disorders such as cystic fibrosis support the theory of evolution?

Cystic fibrosis and other autosomal recessive diseases are not commonly put forward as strong evidential support for the theory of evolution, but being recessive, there is little negative selection pressure to remove the implicated mutations from the gene pool. Another factor to consider is that there are some indications of heterozygous advantage in the form of resistance to cholera, typhoid, diarrhea, and tuberculosis.