Chimerism is a condition in which a person’s body contains two different sets of DNA. It can occur in fraternal twins and as a consequence of bone marrow transplantation. A recent news article describes a unique case of chimerism that could have implications for forensic scientists.
Three months after a man received a bone marrow transplant to treat his acute myeloid leukemia, some tissue samples from his body contained two sets of DNA: his own, and that of the donor. Other tissues had only the recipient’s DNA. Remarkably, the changes in the man’s DNA persisted for several years, and now, some four years after the bone marrow transplant, the DNA in his semen is exclusively that of the donor.
This case could have serious implications for the field of forensic science, especially when investigating sex crimes. For example, if an individual developed chimerism following a bone marrow transplant and then went on to commit a crime, it could mislead forensic investigators.