Not normally a problem. High altitude can cause a problem for some. The trait is thought to confer some benefit in regards to malaria but I don't know if a good study has ever been done. Occasionally a trait patient acts more like a disease patient than you'd think. Not often.
Did you know there are only 5000 Snow Leopards in the wild now and they are confined to Central Asia? However, the effective global population (those likely to reproduce) is less than half that number.