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Why is cord blood important for ethnic minorities?
There are differences in the frequency of certain HLA types among ethnic groups. Therefore, patients are more likely to find a good match among donors from their own ethnic group. African-American patients who need bone marrow transplantation have an especially hard time finding an unrelated bone marrow donor. There are three reasons for this difficulty. The first is simply numerical. African-Americans make up only 12% of the U.S. population and, thus, fewer potential donors are available. The second reason is that there is much greater variation in HLA-types among people with African ancestry than in any other group. And third, some people who have both African and European or other ancestry have combinations of the HLA types that are unique.
It is estimated that at least three times as many African-American volunteer bone marrow donors than Caucasian donors would be needed for African-American patients to have a chance that equals that of Caucasian patients to find a match among bone marrow donor registries. As a result, African-American patients are much less likely to find a matched, unrelated bone marrow donor. With cord blood, however, a partial match is acceptable and most African-American patients can find a suitable cord blood unit. Large public cord blood bank inventories, therefore, can make up for the difficulty in finding suitable bone marrow donors for minority patients.
African-Americans, like everyone else, need transplants for leukemia, lymphoma, and inherited diseases such as severe combined immune deficiency (SCID or "boy-in-the-bubble" syndrome). In addition, African-Americans are more likely than others to suffer from sickle cell disease, a sometimes devastating and crippling disease that eventually will be lethal for most patients. At present, the only cure is a transplant. So far, only a small number of sickle cell patients have benefited from cord blood transplants. But early results are encouraging. Several sickle cell patients have been cured with cord blood from related sibling donors or with cord blood from unrelated donors. Sickle cell patients do better, however, if transplanted early in life. They have a much better chance to survive after the transplant and they are spared the devastating life-time effects of sickle cell disease.
The New York Blood Center's National Cord Blood Program has provided cord blood transplants for over 1,500 patients (more than 1,100 in the U.S.) from an inventory that currently numbers over 25,000. Of U.S. patients transplanted, 19% have been African-Americans. Six of these patients had sickle cell disease.
Patients from other ethnic minority groups also have more difficulty finding a matching unrelated bone marrow donor. Again the problem is numerical. Minority groups simply have smaller numbers from which to draw potential donors. Many Hispanic patients also have ancestry from more than one ethnic group. People from different regions of Asia also tend to differ in their HLA types. For this reason, cord blood banks established in other parts of the world will benefit many U.S. citizens. A Japanese-American, for example, would have a better chance of finding a suitable cord blood unit through the Japanese National Cord Blood Program than from a U.S. Cord Blood Bank.
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