Shortage of Minority Bone Marrow Donors Proves Obstacle
By Josť Alvarado
On the Front Page...
Minority patients suffering from leukemia and other blood-related diseases face limited prospects of finding a donor with matching bone marrow tissue type because of the relatively low number of minorities such as Blacks, Hispanics/Latinos, Native Americans, and Asians/Pacific Islanders represented in the National Marrow Donor Program registry.
"Minorities, in general, are very poorly represented in the NMDP," said Jaime Oblitas, manager of the NIH Marrow Donor Program, which participates in the NMDP. "For a patient to have a successful transplant, donor and patient must be compatible genetically, which sometimes only happens when they both come from the same ethnic or racial group."
NMDP was established in 1987 to facilitate bone marrow transplants between unrelated people. It operates under a contract with the Health Resources and Services Administration and maintains a regional donor center in the Clinical Center department of transfusion medicine. The NMDP registry has information on 2,817,058 volunteers willing to donate about 3-5 percent of their marrow to save the life of a person whose own marrow stops producing the correct amount of various blood cells, the main agents of the body's immune system. At any given moment, there are an average of 3,000 active searches of the NMDP registry. As of July 27, NMDP had facilitated 5,924 unrelated bone marrow transplants in the United States and in several other countries. Of these, 727 have been for minority patients.
Recruiting minorities to be donors is an urgent aim for NMDP, said Oblitas. The program has organized registration drives at NIH during African American history month, and Hispanic heritage month. But these efforts have yet to satisfy the demand among minority patients for donors of similar ethnic or racial backgrounds. Only about 20 percent of the volunteer donors on the NMDP registry are from minority groups, while more than 40 percent of those awaiting transplants are minorities, Oblitas reported.
The level of match for bone marrow must be closer than that for heart, liver and other organ transplants since the donated marrow may attack the recipient's body in what is known as graft-versus-host disease, he explained. This is in contrast to organ transplantation, when the patient's body may reject the organ. Generally, survival rates are in the 40-60 percent range for more than 60 diseases, including several types of leukemia, that would be fatal without bone marrow transplants. NMDP literature says an estimated 30,000 children and adults nationally are afflicted each year with leukemia, aplastic anemia, and other blood-related diseases.
Because the unique characteristics of an individual's marrow are genetically inherited, it would follow that someone from the immediate family would be an ideal donor. But only 30 percent of patients have a family member, generally a sibling, who is suitably matched and able to donate marrow. That makes it crucial for organizations like NMDP to seek out persons of the same racial and ethnic background of the patient, who will most likely have matching human leukocyte antigens (HLAs). HLAs are proteins found on the surface of white blood cells and other tissues that are used to match donor and patient.
Dr. Susan Leitman, head of the blood services section of the department of transfusion medicine, said there is always a need for more bone marrow donors, even among the normally plentiful white donors, who meet the needs of from 75 to 80 percent of all Caucasian recipients searching for a donor. But she pointed out that the low number of volunteer donors among minority groups is made worse by low retrieval and retention rates -- locating and contacting matching donors -- among minorities. While 90 percent of white matching donors can be retrieved, only 70 percent of minority matching donors can be found.
Oblitas says this is a problem when dealing with Hispanic/Latino donors. "The Latino population fluctuates a lot, and it is very difficult to get a hold of people once they have registered. We have many cases of people who have registered in community drives, but when we try to contact them 3 months later, they are no longer living at the addresses they had given. The Hispanic community in the Washington, D.C., area still has not established itself firmly here.
"We should educate minorities in general on the need to register in the NMDP program because many patients from our racial or ethnic groups simply can't find a compatible donor." He says that many minority patients have no choice but to accept transplants from donors with partial HLA matches, increasing the chance of getting the potentially fatal graft-versus-host disease.
The process of registering is as easy as donating blood, according to NMDP literature. A small amount of blood is taken from the volunteer donor at an NMDP-approved donor center or recruitment drive site. The sample is then typed for HLAs and the results are entered in the computerized NMDP registry.
As soon as a doctor finds that a donor's HLA match those of his patient, the donor will be contacted and counseled about the donation process and given a physical examination after a thorough information session. The donor makes the decision to donate and signs an "intent to donate" form.
A simple surgical procedure is used to extract marrow. At an NMDP-approved collection center or hospital, under general or epidural anesthesia, the marrow is removed from the back of the donor's pelvis through a special needle. After collection, the donor is usually kept in the hospital overnight for observation. Donors may experience slight discomfort for a week or so in the lower back. The donor's marrow will replenish itself in 4-6 weeks, according to NMDP literature.
After the donor signs the intent, the patient-recipient undergoes a pre-transplant treatment of chemotherapy and/or radiation therapy to wipe out all disease. Because the treatment also destroys the immune system, the patient will eventually die if he or she does not receive a marrow transplant. The donated marrow is transfused directly into the patient's bloodstream, similar to a blood transfusion. Healthy marrow cells travel to bone cavities, where they begin to grow and replace the old marrow.
All information about the donor is kept confidential. The donor, however, has the opportunity to get to know the patient-recipient about a year after the operation. NMDP arranges such meetings between donor and recipient every year.
For information on how to register or organize a registration drive in your community, call Erika Sparks, recruitment specialist for NMDP, at 496-0572.
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