HIGHLY SENSITIVE DNA TYPING FOR DETECTING-TUMORS TRANSMITTED BY TRANSPLANTATION

DNA typing of a variable number of tandem repeats (VNTRs) and of short tandem repeats (STRs) is a modern forensic method for the identificat ion of biological material. In many cases, amplification by the polyme rase chain reaction (PCR), especially of STRs, allows DNA typing of mi nute amounts of or degraded DNA. Here we describe the successful use o f forensic DNA typing to clarify the origin of a malignant tumor. We r eport two cases of metastatic malignant melanoma of unknown origin tha t developed a few months after transplantation in two recipients of ki dneys from the same donor. Fresh metastatic tissue and blood from the first recipient, reference DNA of the donor, and only paraffin-embedde d tissue from the second recipient were available for analysis. To inv estigate whether the melanoma originated in the donor, DNA analysis of nine polymorphic loci was performed. The results of the analysis show ed that, in both cases, the tumors were genetically different from the recipient DNA but matched the donor DNA. One incident of allele loss was attributed to a mutation event. We conclude that the metastatic me lanoma in both recipients originated in the donor and was transmitted by renal transplantation.