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HLA typing is complex

You have many HLA markers. Half are inherited from your mother and half from your father, so each brother and sister who shares the same parents as you has a 25% chance (1 in 4) of being a close HLA match. Extended family members are not likely to be close HLA matches. But about 70% (7 out of 10) of patients who need a transplant won’t have a suitable donor in their family. 

Research has found that a donor must match a minimum of 6 HLA markers. Many times a closer match is required. A best match is found through detailed testing. 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.

HLA matching is important for transplant

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 (called engraftment) and reduces the risk of a post-transplant complication called graft-versus-host (GVHD) disease. Learn more details about HLA matching.