An alternative to a haplo-identical transplant between related individuals is a matched transplant between unrelated individuals. For Japanese patients, because their island geography increases the likelihood of marriage within a limited gene pool, the chances of finding a 6:6 clinical match are better than for patients in larger gene pools. Of course, much depends upon getting enough donors. Like North American Caucasians, African American and Asian patients are part of a large gene pool, but they are under-represented in the donor pool and only have a 50 percent probability of finding a 6:6 clinical match.

Among different ethnic groups, the probability of finding a 6:6 match is, from the highest to lowest, Japanese (99%), North American Caucasian (93%), African American and Asian (50%).