Man Turns Into ‘Chimera’ As Bone Marrow Transplant Fully Replaces His Semen DNA

A team from Nevada’s Washoe County Sheriff’s Department is currently looking into how changes in DNA following certain medical procedures could influence criminal cases and forensic work.

Chris Long from Reno, Nevada discovered that his blood had been replaced by the DNA of his German donor following a bone marrow transplant, The New York Times reported.

Long, who works at Washoe County Sheriff’s Department, was diagnosed with myeloid leukaemia and myelodysplastic syndromes, leading him to undergo a bone marrow transplant four years ago. His friend and colleague from the crime laboratory, Renee Romero, was interested in the changes that his DNA might potentially undergo following the procedure and tracked them over the years.

“We need to swab the heck out of you before you have this procedure to see how this DNA takes over your body”, she reportedly told Long at the time.

Four years after the operation, Romero and her colleagues at the crime laboratory discovered that not only had Long’s blood changed to the donor’s DNA, which occurred within four months following the procedure, but also parts of his lips and cheeks contained the DNA of the other person, whom Long has never met.

The most shocking discovery, however, was that the DNA in Long’s sperm has now been entirely replaced by his donor’s, with only the hair on his head and chest remaining completely unaffected by the changes.

“We were kind of shocked that Chris was no longer present at all”, Darby Stienmetz from Washoe County Sheriff’s Office told The New York Times.

The findings mean that Long has effectively turned into chimera, a technical term meaning that the person has two sets of DNA.

The research has proved to be crucial for forensic scientists, who have long wondered about the effect that procedures leading to DNA changes and “chimerism” could have on criminal investigations, assuming that each victim or criminal would leave only a single identifying code behind at the crime scene. Long’s case proves that a donor’s DNA can show up in different parts of the body following a bone marrow transplant, which potentially complicates criminal investigations involving people who have undergone similar procedures.