In 1997, researchers in Oklahoma City discovered by accident an antibody, ENAV MNS42 or "Avis," on the walls of red blood cells donated by a Choctaw. Only two other donors, both of Choctaw descent, have been found to carry the antibody, the Tulsa World reported.
OBI Medical Director Dr. James Smith said the finding is significant because it helps the blood bank find blood for patients with the rare antibody.
All three of the Choctaws with the antigen lived in southeastern Oklahoma. The Choctaw Nation has fewer than 200,000 registered members.
"We believe it's possible that the more Choctaw you are, the more chance that there will be this antibody," OBI reference laboratory manager Rosemary Persa told the newspaper. "At this point, it's basically a needle and haystack trying to find donors with this kind of antibody."
Researchers said specific antigens develop to protect carriers from disease and likely are inherited from parents. The findings were originally reported 10 years ago in the journal, Transfusion.