Bone Marrow Donor — Who Can Donate & How Matching Works

Bone marrow donor matching is the process of finding a donor whose tissue type closely matches the patient's. It is based on proteins called HLA (Human Leukocyte Antigens) on your cells, not on your blood group. Doctors compare several HLA markers, often described as a 10/10 or 12/12 match. The closer the match, the lower the risk that the body rejects the new cells or that the donated cells attack the patient. Matching usually starts within the family, because relatives share inherited HLA markers, and moves to volunteer registries if no family donor is found. At CION, every result is reviewed by a tumour board, so matching decisions are made by a team.

Most healthy adults, usually between about 18 and 50 years, can be considered as donors. You should be in good general health, free from serious heart, lung, kidney, or autoimmune disease, and not have an active or recent cancer. Donors are screened for infections such as HIV and hepatitis B and C, and should be within a safe weight range. Donation is always voluntary, and you can ask questions or step back at any point before the procedure. Younger donors are often preferred because their cells tend to give better outcomes. If you are unsure whether you qualify, our team can review your health honestly and tell you clearly what is and is not possible.

No. This is a common and understandable confusion. Bone marrow matching is decided by HLA typing, not by your blood group. A donor with blood type A can still be a perfect HLA match for a patient with blood type O, and vice versa. During a transplant, the patient may even change to the donor's blood type over time. What matters most is how closely your HLA markers match. HLA typing is done with a simple blood test or a cheek swab. So please do not rule yourself in or out as a donor based on blood group alone. If you want clarity, our haemato-oncology team can explain exactly how matching works for your family.

You inherit your HLA markers in two sets, one from each parent. A full sibling inherits from the same two parents, so there is a chance they received the same combination you did. This gives each full sibling roughly a 1-in-4, or 25%, chance of being a full HLA match. Having more siblings can raise the overall odds that at least one matches. Parents and children share only half your HLA, called a half-match or haploidentical, which is used in special transplant protocols. Because matching is inherited, unrelated strangers are far less likely to match closely. This is why testing the family is almost always the first step in the search.

If no sibling or family member is a suitable match, the search moves to volunteer donor registries, which hold HLA details of people willing to donate. Doctors look for an unrelated donor whose HLA closely matches yours. Umbilical cord blood units, which allow slightly less strict matching, are another option. In many centres today, a haploidentical (half-match) transplant from a parent or child is also possible when no full match exists. Finding an unrelated match can take time and depends partly on ethnicity, since registries hold fewer South Asian donors. We will be honest with you about timelines and the options for your specific case, and we walk this journey with you at every step. For some blood cancers, your team may also discuss CAR-T cell therapy, a cellular treatment coordinated via partner centres.

Donation is generally safe, and serious complications are uncommon, though no medical procedure is completely risk-free. There are two methods. In peripheral blood stem cell (PBSC) donation, you receive injections for a few days, then cells are collected from your arm, similar to donating blood components. You may feel bone aches or flu-like symptoms during this time. In a bone marrow harvest, cells are taken from your hip bone under anaesthesia, and you may have lower-back soreness for a few days. Most donors return to normal activity within days to a couple of weeks. The transplant team chooses the method and explains the risks fully before you agree, so you can decide with confidence.

There are two ways to collect stem cells. The first is peripheral blood stem cell (PBSC) collection. The donor receives injections of a medicine for a few days that moves stem cells from the marrow into the bloodstream. The cells are then collected through a needle in one arm, passed through a machine, and the rest of the blood is returned to the other arm. The second method is a bone marrow harvest, done in an operating room under anaesthesia. A needle draws marrow from the back of the hip bone. The body replaces the donated cells within a few weeks. Importantly, marrow is not taken from the spine, which is a common fear. The team picks the method best suited to the patient and donor.

HLA markers vary across ethnic groups, so patients usually match best with donors of similar ancestry. Worldwide registries hold far fewer South Asian and Indian donors than donors of European background. This means an Indian patient who needs an unrelated donor may have a smaller pool to search and may wait longer for a match. The encouraging news is that Indian donor registries are growing, and every new South Asian donor who registers improves the chances for someone in our community. Family testing remains the first and often best option. If a registry search is needed, our team will guide you through it honestly and keep you informed about timelines and realistic expectations.

Yes. A haploidentical transplant uses a donor who shares half of your HLA markers, such as a parent, child, or sometimes a sibling. Because almost everyone has a parent or child who is a half-match, this greatly widens the donor pool, especially helpful when no full match is found. Special preparation and medicines are used to lower the risk of complications like graft-versus-host disease. Haploidentical transplants are now performed in many transplant centres with improving results, though they are more complex than a full-match transplant. Whether this approach suits you depends on your diagnosis, age, and overall health. Our tumour board reviews each case together to recommend the safest path, with transparent costs and no unnecessary tests.

The timeline varies for each patient. HLA typing of the patient is quick, usually a few days for results. Testing siblings adds a short wait while samples are collected and processed. If a family match is found, the process can move ahead in a matter of weeks. If an unrelated registry search is needed, it can take longer, sometimes weeks to a few months, depending on how easily a close HLA match is found. Confirming the chosen donor, with repeat HLA tests and health screening, adds more time. We understand waiting is hard when you are anxious. Our team keeps you updated at each stage and explains honestly what to expect, so you are never left guessing.