Editor, Gazette-Journal:

At any given moment, there is an average of 3,000 active searches for bone marrow donors. Bone marrow is used to treat patients with leukemia, lymphomas, immune deficiency disorders, some solid tumors such as breast and ovarian cancer, and multiple myeloma—which is twice as common among blacks as it is among whites. There are no alternatives to a bone marrow transplant for patients who need this treatment. The bone marrow registries have facilitated nearly 6,000 unrelated matches in the United States and abroad.

Transplant matches are much more complicated than simply having the same blood type. The match needs to come from a genetic level similar to the genes that determine hair and eye color. Because of the unique genetic factors required a sibling offers the best odds of finding a match. But only 30 percent of patients find a suitable match this way.

There are more than six million donors currently registered. More than half of these donors are...