Chimerism in the DNA of buccal swabs from recipients after allogeneic hematopoietic stem cell transplantations: implications for forensic DNA testing

Berger,B.; Parson,R.; Clausen,J.; Zimmermann,B., Decristoforo,L.; Nachbaur,D.; Parson,W.

Buccal swabs are the favorite method for the collection of forensic DNA reference samples, as this approach is straightforward and non-invasive. The reliability of comparative DNA testing using buccal cells as reference is beyond discussion and is based on the fact, that the DNA is the same in every cell of the body. Therefore all exceptions undermining this basic assumption are of vital forensic importance. It has been shown, that in recipients of allogeneic hematopoietic stem cell transplantations (allo-HCT) donor-derived DNA can be found in different tissues, e.g. the buccal mucosa. A mixed chimerism in the DNA from buccal swabs can be seen in these cases. However, a systematic documentation of this phenomenon in forensics is still lacking.