Most of the time, all 35 indicators don't matter. Many are largely the same across the population, so people are likely to match anyway, plus plenty of people never require a blood transfusion. But if you need transfusions to live and you happen to have a rare blood type, it can be a huge problem. That's the situation that two-year-old Zainab, who lives in South Florida, is in right now. She has neuroblastoma, one of the more common pediatric cancers, and she has an unusual blood type. So unusual, in fact, that the organization OneBlood is conducting a global survey to find her an exact match—even her own parents can't give her blood.