HLA typing stands for Human Leukocyte Antigen typing, which is a genetic test used to match patients and donors for bone marrow, cord blood, or organ transplants. HLA are proteins, or markers, found on most cells in the body, and they help the immune system distinguish between the bodys own cells and foreign cells. HLA typing is used to match patients and donors for bone marrow or cord blood transplants. The test identifies certain proteins in the blood called antigens, which are markers on the cells in the body that help the body tell the difference between its own cells and foreign cells. HLA matching is important for transplant outcomes because a close match between a donor’s and a patient’s HLA markers is essential for a successful transplant outcome. HLA matching promotes the growth and development of new healthy blood cells and reduces the risk of a post-transplant complication called graft-versus-host (GVHD) disease. Research has found that a donor must match a minimum of 6 HLA markers, and many times a closer match is required. Because some HLA types are more common than others, some patients may face a greater challenge in finding a matching donor. Some HLA types are found more often in certain racial and ethnic groups.