However, locating a bone marrow donor is more difficult than finding a blood donor. Doctors test the human leukocyte antigen (HLA) of donors to see if they are a match. Each person carries six distinct HLA markers.

HLA is a protein used by the immune system to distinguish between your cells and those of others. A DNA test swab of the inside of your cheek can help doctors determine your HLA. If the six indicators match, the donor’s cells will not be considered “foreign” by the patient’s immune system.