What are the Effects of Medical Treatments on your DNA?

Genetic Genealogy: Medical Impact on DNA

by Andy Lee

We receive our DNA from our mother and father and it sticks with us throughout our life. But is there any way that our DNA can change during our lifetime?

Lots of people have asked about specific situations where DNA can be changed. Today we are going to talk about them and what they mean for your DNA test.

Chimerism

The first way we can have two sets of DNA in our body is through chimerism. A human chimera can happen in a couple of ways. First, in a pregnancy with fraternal twins, if one of the embryos dies early on, some of their cells may be absorbed by the other embryo and then continue in development. This may result in the DNA of different organs looking like they came from two siblings rather than from the same person.  Another way this could happen is if the embryo absorbed some of the mother’s cells or vice versa.

It is unknown how many human chimeras are out there because there is no easy test for it. It may turn out that almost all of us are chimeras and we don’t know it. Through commercial DNA testing, you could find this out for a specific instance.  If your saliva and cheek cells had different DNA than your sperm and egg cells, then your DNA results (from saliva) would show that your children (from sperm/egg) are your nieces/nephews. That’s pretty tripping!

Transplants

The next way that our DNA could change over our lifetime is if we had a transplant. This would give us an organ with the donor’s DNA and the rest of our body with our DNA. Transplant donors and recipients are matched based on immuno-compatibility, genes play a role in this, but it doesn’t mean that the donor and recipient are overall genetically similar.

The simplest transplant that everyone might know something about is a blood transfusion, blood is considered an organ. Depending on if you are A, B, O, or AB, will depend on what type of blood you can get. O can be given to anyone, but people with O blood can only get O. A blood can be given to people with A or AB blood. And so on.

For commercial genetic tests using saliva, you are not going to see a change in your DNA because there aren’t any transplants I know of that affect the salivary glands, tongue or cheek tissue. However, if you are getting a blood-based DNA test the results could be affected if you recently had a blood transfusion or if you have ever had a bone marrow transplant. Blood-based DNA tests are usually done some medical reasons, so you probably need to disclose that you have had a transfusion or transplant.

Environmental Factors

The final way that your DNA can change is through environmental factors. Chemicals and radiation that we are exposed to can change the DNA of cells. It should be noted that these changes are extremely localized. This isn’t changing the DNA of every cell in your body just whatever has been exposed to the damaging chemicals or radiation.

Also, your cells have a way of repairing this damage, so for what you experience every day throughout life, there is no real concern with changing your DNA.

However, in the medical field, there are two processes that expose specific cells to massive amounts of chemicals or radiation: chemotherapy and radiation therapy. Both of these are targeted at killing cancer within the body. And they do that by causing so much damage to the DNA of those cancerous cells that they die. One of the side effects is that they also damage the healthy cells near the cancer cells, so a lot of planning goes into chemotherapy and radiation treatments.

From a commercial genealogical DNA test, there isn’t any concern about these medical procedures affecting your DNA outcome.

I have thought of a specific instance where it might (and that is a big maybe) change your results. If you were being treated for mouth or throat cancer, and you took a test before the treatment, and then a test immediately after (I’m talking hours or days), then it might show a slight difference.  There is a lot of maybes and ifs. However, because our body has such an amazing ability to repair itself, if you took the test a week, a month, or years after treatment, it would look the same as before you received the treatment.

There are some ways that DNA can change to give you potentially false results.  But have no fear, the likelihood of those situations happening are slim to none for the vast majority of people.

If you have been putting off getting a DNA test because you received a transplant or recently underwent cancer treatment… don’t put it off any longer. Your treatment hasn’t changed your DNA. If you have any questions, put them in the comments below.

This post is part of the Research Over My Shoulder video series. 
To watch this video in full, click on THIS LINK

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