DOI: 10.5176/2382-5642_FSCR13.29
Authors: Gomaa R and Sheta A
Abstract:
Violent crimes are frequently characterized by involvement of a struggle between the victim and the perpetrator where biological materials may be exchanged between them. Dealing with mixtures of biological materials of different sources is encountered in homicide, crime investigations, in mass disasters exploration as well as sexual assaults. Sex determination of victims and assailants is mandatory. The current study investigated the sensitivity and utility of the conventional PCR for identification of male DNA in different dilution samples of male- female mixtures of human blood using a male specific DNA marker. Subjects and methods: Whole peripheral blood was collected from five adult apparently males and five adult apparently females, each male blood sample was mixed with one female blood sample in five serial dilution mixtures in ratios of 1:1, 1:10, 1:20, 1:50 and 1:100. PCR amplification of DYS14 gene located on Y-chromosome was used to identify the male DNA in all mixtures of blood. Androgen receptor (AR) gene PCR amplification was used as an internal control in all mixtures. Results: Identification of male DNA evidence in mixture samples was verified by detecting the specific band size of the Y-chromosome DYS14 gene identical to the PCR product of pure male sample amplification. Androgen Receptor gene was used as an internal control that was amplified in all mixture dilutions same as in pure female evidence sample. The male component (minor component) of all mixture dilutions were successfully detected by conventional PCR. A good DNA yield (as evidenced by PCR amplification and gel electrophoresis) was obtained in all male to female mixture dilutions; 1:1, 1:10, 1:20, 1:50 and 1:100 with slight decrease in DNA yield quality only restricted to the maximum dilution mixture of 1:100 male to female. Conclusion: The use of conventional PCR in this protocol was shown to be sensitive enough to detect male DNA diluted in female biological samples up to 1:100. Thus, conventional PCR is advantageous compared to the highly sophisticated molecular techniques which might not be necessarily available in every laboratory, particularly in the developing communities. Therefore, the conventional PCR is proved to be useful as a preliminary step in forensic investigations before proceeding to costly advanced technology.
Keywords:
human identification, male DNA, female male mixture, forensic sample, PCR, DYS14 gene, Androgen Receptor gene
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