N. Dimo-Simonin, F. Grange and C. Brandt-Casadevall
Institut Universitaire de Médecine légale, Lausanne, Switzerland
After a legal request concerning a sexual assault case with only one cytological smear stained with Papanicolaou as material available for identification, experiments were performed to evaluate the efficiency of some PCR-STR and PCR-Sequence Polymorphism for the identification of stained Pap smears and postcoital slides with the Chelex extraction.
Three cytological staining techniques (Papanicolaou, May-Grünwald-Giemsa, Hematoxylin-Eosin) and one forensic staining technique (Baecchi) were used after chemical or heat fixation of the slides.
The following PCR-Systems were determined: HLA-DQa, PolyMarker, Amelogenin, HUMTH01, HUMVWFA31, HUMF13B and HUMFES/FPS.
The chemical and heat fixation gave no significant difference in DNA yield.
All the stained slides gave a good DNA yield, with the exception of the Baecchi stain as the DNA extracted was clearly degraded and lacked high molecular DNA.
For the cytological staining, HLADQa and PolyMarker gave a success rate between 80% and 100%. With the exception of the HUMFES/FPS, which is less sensitive, the success rate of the STR-Systems fluctuated between 63% and 100% with the highest average rate of 95% obtained with the HUMTH01.
However, for the Baecchi stained slides, since the DNA was degraded and in a small quantity (about 1 ng), only HLADQ and HUMTH01 were tested. The HUMTH01 gave the best success rate at 65% while the HLADQa dropped to 50%.
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