Gift of Life Marrow Registry finds matching blood stem cell and marrow donors for patients who are battling life-threatening blood diseases and immune disorders. Matches for transplants are based on the human leukocyte antigens (HLA), a key part of the immune system.
We are sometimes asked whose DNA the recipient will have after the transplant, their own or the donor’s DNA. With many medical questions, the answer is not simply “it’s one or the other,” and in this case, it’s “both.”
As a refresher, DNA (deoxyribonucleic acid) is a molecule found in the nucleus of cells that carries the genetic information of every living organism, from one-celled microbes to plants to humans. DNA is composed of four types of nucleotides: adenine (A), thymine (T), cytosine (C), and guanine (G). These nucleotides form pairs (A with T, and C with G) that coil up into the familiar double helix structure. The DNA sequence determines the traits and characteristics of an organism, such as hair and eye color, as well as determining the immune system. Every organism has a unique DNA profile, although identical twins share the same DNA.
Blood stem cell and bone marrow transplants are medical procedures that replace the damaged or diseased stem cells of a patient with healthy ones from a donor. Blood stem cells are immature cells that can develop into all the different types of blood and immune system cells our bodies need to function, such as red blood cells, white blood cells, and platelets.
These transplants can treat many life-threatening conditions, such as leukemia, lymphoma, sickle cell disease, and immune system disorders. The goal is to restore the normal function of the blood and immune system, and potentially cure the underlying disease.
There are two main types of blood stem cell transplants: allogeneic and autologous. In an allogeneic transplant, the donor cells come from another person, about 30% of the time from a close relative, and 70% of the time from a matched, unrelated donor, such as a volunteer in Gift of Life’s registry. In an autologous transplant, the donor cells come from the patient themselves.
Some people wonder whether this type of transplant can change the DNA of the recipient. The answer involves several factors, such as the type of transplant, the source of the donor cells, and the extent of the DNA testing.
Except in the case where the transplanted cells come from the recipient or the recipient’s identical twin, all donated cells will have different DNA from that of the recipient. The recipient's DNA does no change, but after the transplant, the recipient will have two sets of DNA in their body: their own DNA is found in most of their cells, and the donor’s DNA is found in their blood and immune system cells. This state of having two types of DNA is called “chimerism”, after the hybrid creature from Greek mythology.
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Chimerism is detected by DNA testing on different types of tissues, such as blood, hair, or skin. In a transplant recipient, it is a sign that the transplanted cells are successfully established and producing new blood cells. Chimerism testing can also help determine the risk of complications such as graft-versus-host disease.
In an autologous transplant, the transplanted cells came from the patient, so there is no additional DNA in their body after the transplant.
Since the change in DNA is limited to the blood and immune system cells, it does not affect the rest of the body; there is no change to the identity of the recipient. However, if the recipient plans to do genealogical genetic testing, it is best done before the transplant, as results after a marrow transplant can be inconclusive or incorrect due to the presence of donor DNA in blood or immune cells that are part of the test sample.
Because finding genetic matches for patients is so rare, the more donors who join the registry, the more lives can be saved.
If you are 18-35 years old and in general good health, you can apply to join the registry for your chance to become someone’s hero. The process is simple: order a registration kit and you’ll get a package containing cheek swabs – no blood test is needed to join. Just complete the online health questionnaire, swab your cheeks, and return the swab kit to us using the postage-paid envelope.
If you match a patient in need, now or in the future, we will contact you and invite you to donate blood stem cells or bone marrow to save that person’s life.
Order your cheek swab kit here!
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8065704/
https://www.genome.gov/genetics-glossary/Deoxyribonucleic-Acid#
https://www.ancestry.com/c/dna-learning-hub/dna-test-bone-marrow-stem-cell-transplant#