BIOL2151 - Forensic DNA Analysis: STR Loci Requirements in Cities

This report investigates the number of STR loci required for forensic DNA analysis in cities with different population sizes, specifically Melbourne, Mumbai, and Papua New Guinea. The analysis uses statistical data from the ANU STR database and relevant literature. Key genetic loci such as CSF1PO, D3s1368, D16S639, and vWA are identified as potential markers for differentiating genetic profiles among the populations. While 15 STR loci appear sufficient, the report suggests that a larger number of informative genetic loci may be needed to effectively discriminate populations, especially considering increasing populations and cross-border movement. Desklib provides access to similar solved assignments and resources for students.

Short tandem repeat sequences (STR) are highly variable regions of DNA, having length of
up to 250-400 bp. The autosomal STR markers are referred to as highly effective tools for
establishing genetic identity, and therefore used in forensic investigations(Yang et al., 2017).
These shorter sequences are relatively easier to amplify and multiplex in PCR, and have been
used to construct forensic DNA databases, for the identification of criminals. Therefore, it is
the uniqueness of a person’s DNA and its numerical codification which makes the bases for
establishing the probabilities, which assist in solving crimes (Gill, Sparkes, & Tully, 2001).
For the present analysis to determine the required number of STR loci the cities chosen
comprise of Melbourne, Mumbai, and Papua New Guinea. The population data for the
respective population was also collected. As per the 2011 census the population of Mumbai
was found to be 12442373 (Census Organization of India, 2018). Melbourne has a population
of 4.5 million (Australia population, 2018), whereas PNG has a population of 7,275,324 as
per 2011 census (National Statistics Office, 2018).
The statistical calculations for the different populations over the set of 15 different loci were
performed. In the wake of findings from the allelic frequencies from the ANU STR database
were studied in comparison with the cities of choice, that is, Mumbai, Melbourne, and PNG
the genetic loci CSF1PO, D3s1368, D16S639, and vWA showed high degree of feasibility in
serving as potential genetic markers for successfully differentiating between the genetic
profiles obtained from the respective populations. The other loci also indicated towards
genetic differentiation, but comparatively lower degree of isolation, as the Fst values neared
0. Thus, given 15 STR loci prove to be sufficient in differentiating among the increasing
populations. However, to predict the ancestry information, better measures other than Fst
divergence are required (Algee-Hewitt, Edge, Kim.J., Li, & Rosenberg, 2016). However, in
the wake of increasing populations, movement of people across the borders, and population
structures a larger number of highly informative genetic loci is required for successfully
discriminating the populations from each other.
Reference:
Algee-Hewitt, B. ., Edge, M. D., Kim.J., Li, J. Z., & Rosenberg, N. A. (2016). Individual
Identifiability Predicts Population Identifiability in Forensic Microsatellite Markers.
Current Biology, 26(7), 935–942.
Australia population 2018. (2018).
Census Organization of India. (2018). Mumbai (Greater Mumbai) City Census 2011 data.
Gill, P., Sparkes, R., & Tully, G. (2001). DNA Profiling in ForensicScience. Encyclopedia
of Life Sciences. Nature Publishing Group.
National Statistics Office. (2018). Population.
Yang, X., Zhang, X., Zhu, J., Chen, L., Liu, C., Feng, X., … Liu, C. (2017). Genetic
analysis of 19 Xchromosome STR loci for forensicpurposes in four Chinese
ethnicgroups. Scientific Reports.