How can Liron – an Israeli – be a perfect DNA match on Israeli charity Ezer Mitzion’s bone marrow donor database for Jonathan – a South African with leukemia? Even Jonathan’s siblings aren’t a match. When they meet this Pesach they may discover that their Litvak grandparents were not strangers at all.
http://www.ezermizion.org/blog/a-bone-marrow-transplant-between-strangers-or-perhaps/