The impact of chimerism in DNA-based forensic sex determination analysis

Sex determination is the most important step in personal identification in forensic investigations. DNA-based sex determination analysis is comparatively more reliable than the other conventional methods of sex determination analysis. Advanced technology like real-time polymerase chain reaction (PCR) offers accurate and reproducible results and is at the level of legal acceptance. But still there are situations like chimerism where an individual possess both male and female specific factors together in their body. Sex determination analysis in such cases can give erroneous results. This paper discusses the phenomenon of chimerism and its impact on sex determination analysis in forensic investigations.

A Case of DNA Chimerism Analysis as a Marker of Donor Lymphocyte Infusion / 대한혈액학회지

Donor lymphocyte infusion (DLI) has some benefit effects as graft-versus-leukemia effect, reducing the relapse of leukemia and inducing of a complete remission. But it has also a graft-versus-host-disease (GVHD) effect. So it is required a proper marker test when DLI is performing. The DNA chimerism analysis can be a marker test in DLI. Variable number of tandem repeats (VNTR) are highly polymorphic DNA markers in the human genomic DNA and used as primers of DNA chimerism analysis. A 43-year-old male who had been diagnosed acute myelogenous leukemia was transplanted with allogeneic peripheral blood stem cells. The initial chimerism analysis showed complete chimerism but it changed to mixed chimerism after 7 months of transplantation. We predicted the relapse of leukemia and performed DLI. The patient could obtain the complete chimerism after DLI. We report a case of chimerism analysis which was useful to predict the relapse of leukemia and perform the DLI.

The Discrimination Power and Effectiveness of 3 Kinds of LTR Primers in the VNTR-PCR for Evaluation of the Engraftment of Allogeneic Peripheral Blood Stem Cells Transplantation / 대한임상병리학회지

BACKGROUND: There are highly-polymorphic DNA markers in the human genomic DNA, known as the variable number of tandem repeats (VNTR). The VNTR markers can be used to evaluate the engraftment of stem cells. We evaluated the discrimination power of 3 types of long-tandem repeat (LTR) and tried to predict underlying disease relapses by DNA chimerism. METHODS: Twenty-nine patients were transplanted with allogeneic peripheral blood stem cells (PBSCs) and their related donors were tested. We used the three long-tandem repeats (LTR) D1S80, D1S111, and YNZ22 for VNTR-PCR. The informative test was performed before transplantation. The chimerism analysis was performed on days +30, +60, +90, and +180 after transplantation. RESULTS: The most informative marker was D1S80 with 55.2% discrimination potential. The power of discrimination was 79.3% in the combination of 3 LTRs. Twenty-two cases were tested for DNA chimerism analysis. When the complete chimerism was represented, the engraftment was more successful and when the mixed chimerism was represented, the underlying disease relapse rate increased. CONCLUSTIONS: DNA chimerism analysis was useful to evaluate the marrow status of patients. It also served as an indication for donor lymphocyte infusion. However, compared to unrelated allogenic PBSCT, the discrimination potential for the combination of 3 LTR loci was lower in the related allogenic PBSCT. Therefore, it is thought that additional short-tandem repeats and DNA sequencing are required for more discrimination power especially in related transplantation cases.