What is a Related Donor?

The donor is the name given to the donator in cases where blood, stem cell, and organ transplantation are required in medical science. The related donor is when people with blood ties are donors. In organ transplants, the condition of being a relative is also sought if the donor is alive. However, as long as tissue and blood compatibility in the bone marrow and blood transfusions, donations can be made from unrelated donors.

Importance of Compatible Transmitter

The immune system plays an essential role in the success of the transplant. The immune system usually keeps us healthy by destroying anything it finds foreign in the body, such as bacteria or viruses. A normally functioning immune system also perceives cells from other people as foreign.

If there is no close tissue type compatibility between the donor and the recipient, the patient’s immune system perceives the new stem cells as foreign and destroys them. This is called graft rejection and can lead to the failure of the grafted cells. This is rare as most of the immune system is destroyed by pre-transplant treatment (chemotherapy and radiation therapy).

Another problem that may occur is that when the donor cells make their immune cells, the newly formed cells can perceive the cells in the patient as foreign and turn them into enemies against their nests. This type of attack is called graft-versus-host disease. The given stem cells attack the transplanted person’s body. Therefore, every effort is made to find the most suitable donor possible.

Resources in Living Donor Transplantation

1st-degree relative: Our mother, father, and children are first-degree relatives.

2nd-degree relatives: Our siblings, grandchildren, and parent line are our relatives with second-degree blood ties.

3rd-degree relatives: The children of our siblings, namely nephews, uncles, aunts, and uncles, are our third-degree relatives.

4th-degree relatives: Children of our 3rd-degree relatives become our 4th-degree relatives.

In line with this ranking, the probability of the tissue being taken from related donors being compatible with us increases.


Are Related Donors Better for Transplants?

Sibling donors are generally better for stem cell transplants than unrelated donors. The exact comparison depends on the patient’s diagnosis and the stage of the disease. Two necessary measures of patient outcome after a stem cell transplant are long-term survival and the amount of graft-versus-host disease (GvHD) the patient is exposed to. Sibling donors trigger less GvHD, resulting in better post-transplant quality of life. Also, sibling donors are found faster than looking for an unrelated donors, and patients survive better when they are transplanted faster after diagnosis.

For many adult cancers, outcomes from sibling transplants are comparable to results from unrelated donors, but sibling donors have a slight advantage. One large study was by Weisdorf et al. 2002, for over 2900 patients with CML leukemia. When correcting for all other factors, the survival with sibling donor vs. unrelated donor was 68% vs. 61%.

However, sibling donors have a distinct advantage in pediatric transplants for inherited disorders. The European Blood and Marrow Transplantation Group (EBMT) announced in 2011 that the three-year survival rates were 95% from a sibling donor and 61% from an unrelated donor.