Originally Posted by
OrAclE
It's not always a negative. People who are heterozygous with sickle cell disease are immune to, I think, malaria. Still a disorder, but it can be beneficial.
I would still call sickle cell anemia a mostly negative mutation though. But yea, it does have advantages.
Originally Posted by
Meamme0
Not every disorder is caused by mutation. Some disorders are caused by diet or social or physical environments.
Almost all disorders have underlying genetic causes. Especially the ones mentioned here.