It is a challenge for many patients to find a suitable donor. Ideally the patient and donor would have identical or closely matched tissue type. Tissue type can be described as the genetic markers on the surface of white blood cells otherwise known as HLA-antigens or human leukocyte antigens. In the late 1950's a French scientist described the first human histocompatibility antigens. Over time it was discovered that each individual inherits three antigens, HLA-A, B, and DR, from each parent. The ability to match potential donors with patients/recipients requires that six antigens of a potential donor match with the six antigens of the patient/recipient. Other antigens do play a role in the outcome of transplant, however, HLA-A, B, DR also known as the "major histocompatibility complex" are critical in determining transplant outcome and therefore are strongly considered when searching for a match. In general, the more precise the match between donor and recipient tissue type, the less risk there is for Graft-versus-Host Disease or graft rejection. A matched sibling or related donor is usually the most desirable however, not everyone has a sibling or relative with matching tissue type. 

National Marrow Donor Program

After the first successful unrelated transplants performed at Memorial Sloan Kettering in 1973, the need to have an established unrelated transplant registry became clear. In 1984 the National Organ Transplant Act was passed. Included in that Bill was an establishment of a National Volunteer registry of donors. The National Marrow Donor Program was established in 1986 after Representative William Young secured a 1.3 million dollar grant from the United States Navy. The National Marrow Donor Programs' mission today is "To facilitate successful hematopoeitic cell transplants from volunteer donors as a life saving therapy for all racial and socioeconomic backgrounds". As of April 2000 the NMDP has facilitated over 9000 unrelated stem cell transplants and has a total number of 3,947,113 volunteers. The racial/ethnic designation and numbers of volunteer donors, as of December 1999, is as follows; African-American - 305,440, American Indian/Alaska Native - 51,695, Asian/Pacific Islander - 227,146, Caucasian - 2,154,297, Hispanic - 305,724, Multiple Race/Other - 64,562, Unknown - 740,285. The NMDP continues to be a resource for patients, families, donors, and as advocates in the transplant community.