A single gene mutation offers some European Caucasians immunity to human immunodeficiency virus (HIV). How does the gene mutation change cells to block HIV from entering them? Can you think of any way O'Brian's team could determine if Europeans who died during the black plague were missing the genetic mutation for HIV immunity? Do you think a genetic test should be developed so people can find out whether they are immune to HIV? What might be the pros and cons of such a test?
