I would imagine this is a huge problem in transplant- especially bone marrow transplant. They need to match HLA (human leukocyte antigen) and the better they match, the better the transplant outcome. HLA matching is difficult no matter what race, but Asian, South Asian, Arab; jew, etc., mixing (aw jeesh I forgot the neegar) all that genetic material is going to make some transplants a hassle. Of course, you can always call China and they'll tissue match a wyghur for you...