A bone marrow match occurs when a bone marrow donor has marrow that matches someone who needs a bone marrow transplant. People who are diagnosed with a serious immune system, blood or genetic disease may choose to have a bone marrow transplant as one of their treatment options. A bone marrow transplant replaces unhealthy blood-forming cells with healthy cells from a donor. Once a person has decided to proceed with a transplant, they must find a donor with a successful bone marrow match.
When matching bone marrow from a donor and a patient, doctors look for compatible HLA tissue types. HLA stands for human leukocyte antigen, which is an inherited protein found on most cells in the body. These proteins act as markers and indicate which cells belong to the body and which do not. Because these markers are hereditary, each person has two sets that include one from each parent.
To test a person's bone marrow, doctors look at six HLA antigens, but many transplant centers test for eight or ten antigens. For a successful bone marrow match, at least five antigens must match. The process used to ensure the best possible match for a donor and recipient is called confirmatory typing. Bone marrow transplants that use another person's marrow are called allogeneic bone marrow transplants and are the most popular.
Because HLA tissues are genetic, most doctors first look for donors within the family, with the best chance of finding a sibling. It is important to note that not everyone with siblings will have a successful match. According to the National Bone Marrow Donor Program, only 30 percent of bone marrow recipients will find a successful match within their family. In the event that no match is found within the family, doctors review the national bone marrow registry. Finding a successful bone marrow match in the registry is sheer luck. Sometimes there is an immediate match, and sometimes recipients have to wait weeks or months before finding a match.
It is a common misconception that donating bone marrow is a painful procedure. A marrow donor who has been matched with a recipient must undergo surgery. Donors are given anesthesia and hollow needles are used to remove liquid marrow from the back of the pelvis. There will be mild lower back pain for a few days. Most donors return to their normal daily activities within a few days and can expect their bone marrow to fully regenerate in four to six weeks.