After bone marrow transplant, local man now has two sets of DNA

Published: Dec. 20, 2019 at 4:37 PM PST
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After a bone marrow transplant in 2015, Chris Long, learned that his DNA had changed. He now had two sets, his and his donor's, who lives 5,000 miles away.

"As I went through the transplant process I'd put a little blood on a cotton ball, label them day one, day two, all the way to day 20 to see each day what was different and it was pretty amazing to see my DNA drop and the new DNA numbers come up," he said.

Long was diagnosed with leukemia is 2014 and received the transplant about a year later. Long works as a project coordinator for technology services at the Washoe County Sheriff's Office. His colleagues asked if they could monitor the changes.

"By day 20 I was completely gone and my blood had all of my donor's DNA," he said.

That was exactly what his doctor's wanted. The healthy blood replaced the weak blood. With that replacement came his donor's DNA.

"Went ahead and started testing more areas like skin, and hair and other fluids and there were some kind of amazing results," Long said.

Long is now a chimera, which is the term for a person with two sets of DNA.

"In Chris' body he now has a mixture of two sets of DNA. He has his DNA in most of his body and the DNA of his donor at the same time," David Jackson, Supervising Criminalist at the WCSO, said.

So could Long ever be implicated in a crime he didn't commit?

Jackson said there is no need to worry because there are safeguards in place.

"So even though we might see a mix of DNA, which is what we've seen in our lab when Chris is being tested, there are techniques that we can figure out by working together with the detectives and also by looking through our DNA profiles," Jackson said.

Long's blood wasn't the only thing that changed.

"Some of his body fluids contained more of his donor's DNA profile and sometimes up to 100 percent," Jackson said.

It is common and expected for this to happen with donor recipients like Long.

"We know it happens and we know his DNA profile will be taken over and we rarely get the opportunity to observe it so for us to see it is not shocking but fascinating," Jackson said.

Five years after his diagnosis, Long is now cancer free. He hopes to meet his donor this summer and said he is grateful for the gift he received from him.

"Without his donation I would not be here today and his comment back was you don't need to thank me this is just what we're supposed to do," Long said.

Long urges everyone to become a donor. It's an easy process to do and you could save someone's life. If you'd like to learn more about or sign up to become a donor you can do so at


Copyright KOLO-TV 2019

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