Question

How many STR(short tandem repeats) loci are required to assist in solving a crime in a series of citites of increasing population size such as Canberra, Papua New Guinea and Indonesia using an online STR database

Check list of the minimum statistical analysis required

• Standard Statistics: Number of alleles Na, observed heterozygosity HO, expected heterozygosity

HE for all loci. Also report the mean of these values over the loci.

• DNA Profile probabilities DPP, across all 15 loci for two different individuals.

• Cumulative PI for increasing combinations of the 15 loci.

• Compute the odds for all probabilities that you calculate (e.g. DPP and PI).

Assess whether the STR database populations approximate HWE (F=0).

• Compute the degree of differentiation (FST) among the populations in the database.

Answer 1

15 STR. Evolutionary and cultural history can affect the genetic characterstics of the population and influences the frrequency of different variants at a particular genetic marker(allele frequency). These characters directly influence the strength of forensic DNA evidence and make the availability of suitable allele frequency information for every discrete country for jurisdriction highly relevant. Population sub-structure within Indonesia has not been well characterised but should be expected given the complex geographical, linguistic, and cultutral architecture of the Indonesian population. Here we use STR(short tandom repeats) markers to identify a number of distinct genetic sub-population within Indonesia and calculate appropriate population sub-structure correction factors.