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This Is What It’s Like Living With Two Types of DNA

There was little hope for blood cancer patients until Donnall Thomas came along.

Ronni Gordon

Image: Qimono/Pixabay

In 2015's Lifetime Thriller "Bad Blood," a woman falsely accused of murder realizes that the leukemia patient to whom she donated bone marrow has a match for her blood type and is using this new identity to implicate her in his crimes.

In a 2004 episode of "Law and Order SVU," a rapist almost got away with a crime because the DNA from a cheek swab did not match the DNA in the blood at the crime scene. But investigators got their guy when they learned he had a bone marrow transplant, making the DNA in his blood different than in the rest of his body.

These criminals are chimeras, people with two types of DNA. I know about this because I am also a transplant recipient and therefore also a chimera. I got leukemia, got chemotherapy to eradicate it, and got a stem cell transplant (also called a bone marrow transplant). My blood type changed to my donor's, with the DNA in my blood becoming different from the DNA in my cells.

A Chimera was a creature in Greek mythology usually represented as a composite of a lion, goat, and serpent.

The real-life drama does not concern criminal minds as in TV and film. Rather it is a between "team graft" (the donor) and "team host" (the recipient), inside the patient's body: graft vs. host disease, or GVHD. Some GVHD is good – a sign that the donor cells are actively seeking and destroying any possible invading cancer cells (graft vs. leukemia effect). But too much can be harmful and even fatal. For me, this means lifelong treatment for GVHD of the skin, liver and digestive system.

A Chimera was a creature in Greek mythology usually represented as a composite of a lion, goat, and serpent.

According to the Seattle Cancer Care Alliance, "Contemporary use of the term 'chimerism' in hematopoietic cell transplant derives from this idea of a 'mixed' entity, referring to someone who has received a transplant of genetically different tissue. Also called blood stem cells, hematopoietic cells are immature cells that can develop into white blood cells, red blood cells, and platelets."

Ronni Gordon at her daughter's graduation. Image: Ronni Gordon

Not too long ago, there was little hope for blood cancer patients.

We chimeras owe our existence to the persistence of a Harvard-trained researcher later called The Father of Bone Marrow Transplantation. In 1957, E. Donnall Thomas published a report of a new approach to blood cancer treatment: radiation and chemotherapy followed by the intravenous infusion of bone marrow.

"That publication represented the beginning of a long series of laboratory and clinical investigations; more than a decade would pass before the procedure achieved its first successes," Frederick R. Appelbaum, M.D, wrote in an appreciation in The New England Journal of Medicine.

Thomas, who later won a Nobel Prize for his discovery, once said, "In the 1960s in particular and even into the 1970s, there were very responsible physicians who said this would never work. Some suggested it shouldn't go on as an experimental thing."

In 2013, The Worldwide Network for Blood and Marrow Transplantation announced a landmark: a total of 1 million stem cell transplants had been performed worldwide.

Approximately 24,000 patients receive a donor's cells annually. According to Be The Match (formerly The National Marrow Donor Program), of the 50,000 patients transplanted annually, 53 percent are autologous—using the patient's own stem cells —and 47 percent are allogenic, using someone else's cells or umbilical cord blood.

At first, unless patients had an identical twin with matching tissue types, their immune system would destroy the transplanted cells as foreign, or the transplanted cells would destroy the patient's organs. But Thomas figured out how to use immune suppressant drugs to keep this from happening. And he recognized the importance of matching donors' genetic markers with recipients, helping to inspire the creation of a national bone marrow donor registry, which is how I got my donor.

"Distinguishing the cells of the body that cause graft versus host disease (GVHD) and those that are important to fight leukemia/lymphoma/ tumor (GVL/GVT) has been a major area of research for many years," said Linda Burns, M.D., Vice President and Medical Director of Health Services Research at Be The Match.

At first, unless patients had an identical twin with matching tissue types, their immune system would destroy the transplanted cells as foreign, or the transplanted cells would destroy the patient's organs.

"Scientists have a better understanding now of how to prevent GVHD and maintain the graft's ability to fight any residual cancer cells," she continued in an email. "Clinical research studies are ongoing in this area, including ones that select the cells from the graft that are critical, as well as ones that incorporate chemotherapy or immunotherapy to reduce GVHD while maintaining the GVL/GVT effect and hence prevent relapse."

As I wrote in my New York Times Lives essay, I got leukemia in 2003. I had chemotherapy and a transplant that year but relapsed twice, leading to my fourth transplant eight years ago.

Fixing one problem often creates another. I take prednisone to help control my GVHD. But prednisone suppresses the immune system, leading to multiple squamous cell skin cancers, some needing surgery. Prednisone also weakens your muscles; when I was originally on higher doses than the 1 milligram I take now, I could barely stand up and sit down in a chair, and I fell more than once. And GVHD of the skin caused my abdomen to harden like a bowling ball, my hands to puff up and the skin on my thighs to resemble bubble wrap.

I didn't realize how much my skin had already tightened until I began a treatment called extracorporeal photopheresis, or ECP. This entails lying still for three hours with a big needle in your arm while a machine draws your blood out through a tube. The white cells are separated, exposed to UV light and returned with their DNA altered to calm them down.

When I started a year and half ago, I went twice a week for three months, gradually cutting back to every other week as my skin started to soften. The closest center where I can get this done is 90 miles from me. It is almost a part-time job.

Sometimes the needle, like all the side effects, hits a nerve. But mostly I can't complain. Back in 2003, I didn't even know if I would make it to my oldest son's high school graduation that year. But I did. I also saw my three children graduate from college and welcomed a baby granddaughter into the world. Being a chimera is a small price to pay.

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