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We analyzed forensic DNA samples from four cases of sexual assault, using the Y-chromosome-specific human DNA markers and a panel of autosomal short tandem repeats (STRs). The presence of male contribution was evaluated by the analysis of the Amelogenin locus. A panel of tetrameric Y-STR (DYS19, DYS390, DYS391, DYS392, DYS385, DYS389I and II) was used in further analysis of samples, increasing the efficiency of the forensic genetic analyses. It was possible to identify a partial or full Y-profile of the rapists in different DNA mixtures when genetic profile could not be detected by autosomal STRs. However, in the case of male/male DNA mixture, only the victim's Y-profile could be obtained because the DNA of the offenders was present in low amounts. When the mixture contained different male/male proportion of DNA, only the full profile of the major component could be detected. In cases where male/female DNA mixed stains contained a sufficient amount of male DNA, the analysis of autosomal STRs was adequate enough to identify the full profile of the rapist. Our experience shows that the main advantage of the Y-STR approach is its ability to detect the male component in the mixed stains when the DNA of the male contributor is present only in a very small amount.

We have recently introduced a new protocol for analyzing all core loci of the Federal Bureau of Investigation's (FBI) Combined DNA Index System (CODIS) with an infrared (IR) automatic DNA sequencer (LI-COR 4200). The amplicons were labeled with forward oligonucleotide primers, covalently linked to a new infrared fluorescent molecule (IRDye 800). The alleles were displayed as familiar autoradiogram-like images with real-time detection. This protocol was employed for paternity testing, population studies, and identification of degraded forensic samples. We extensively analyzed some simulated forensic samples and mixed stains (blood, semen, saliva, bones, and fixed archival embedded tissues), comparing the results with donor samples. Sensitivity studies were also performed for the four multiplex systems. Our results show the efficiency, reliability, and accuracy of the IR system for the analysis of forensic samples. We also compared the efficiency of the multiplex protocol with ultraviolet (UV) technology. Paternity tests, undegraded DNA samples, and real forensic samples were analyzed with this approach based on IR technology and with UV-based automatic sequencers in combination with commercially-available kits. The comparability of the results with the widespread UV methods suggests that it is possible to exchange data between laboratories using the same core group of markers but different primer sets and detection methods.

Abstract: STR analysis is currently used in paternity testing. We report a case of an apparent paternal inconsistency due to low discrimination power of heterozygosis status at D12S391 locus. [Copyright &y& Elsevier]

• Identification of specific body fluids is useful in reconstructing criminal cases. • Three-year-old child supposedly victim of sexual assault with digital penetration. • mRNA analysis permits to identify the tissue of origin of the biological material. • Identification of vaginal secretion confirms the man had raped the little child. DNA profiling can identify an individual from a sample of biological material but it does not reveal what body fluid or tissue source the DNA profile originated from. In many cases it is important to know from what body fluid or tissue the DNA profile originated in order to provide crucial information necessary to the investigation, especially in cases where the victims are not able to give information about the dynamics of the event. For this purpose messenger RNA (mRNA) analysis has been shown to be a suitable method for the identification of body fluids, resulting in a trend to overcome the conventional approaches. Here we present the first report about case regarding a three-year-old child supposedly victim of a sexual assault with digital penetration. Thanks to the use of the combined DNA profiling and RNA analysis it was possible to demonstrate the sexual assault suffered by the victim. [ABSTRACT FROM AUTHOR]