Variation at three short tandem repeat (STR) loci in Australians: forensic and ethnic considerations

Y-chromosome 10 locus short tandem repeat haplotypes in a population sample from Sicily Italy

This study reports the first data on Y-chromosome-specific short tandem repeat (STR) haplotype frequencies, in the population of the island of Sicily (Italy), based on the combination of alleles at the following 10 Y-chromosome loci DYS19, DYS389I, DYS389II, DYS390, DYS391, DYS392, DYS393, DYS437, DYS438, and DYS439. In a total of 117 males, 108 unique haplotypes were observed, with 99 of them being singletons. The 10 locus haplotypes generated a diversity value of 0.9987 and discriminatory power (DP) of 92.30%. The data on the seven of the 10 polymorphisms (DYS19; DYS389I; DYS389II; DYS390; DYS391; DYS392 and DYS393) that have been most studied in worldwide populations were compared with similar data from neighboring Mediterranean populations in order to address the question of shared ancestry, gene flow and population affinities. Overall, results indicate Sicily is closest genetically to the mainland Italian population but also with evidence of a significant African component in the male gene pool. These findings are consistent with those obtained from other genetic markers (autosomal and mitochondrial DNA as well as the classical blood groups) and also with the recorded settlement history (either peaceful or due to invasion) of the island.

Implications for DNA identification arising from an analysis of Australian forensic databases

Previous analyses of Australian samples have suggested that populations of the same broad racial group (Caucasian, Asian, Aboriginal) tend to be genetically similar across states. This suggests that a single national Australian database for each such group may be feasible, which would greatly facilitate casework. We have investigated samples drawn from each of these groups in different Australian states, and have quantified the genetic homogeneity across states within each racial group in terms of the "coancestry coefficient" F(ST). In accord with earlier results, we find that F(ST) values, as estimated from these data, are very small for Caucasians and Asians, usually <0.5%. We find that "declared" Aborigines (which includes many with partly Aboriginal genetic heritage) are also genetically similar across states, although they display some differentiation from a "pure" Aboriginal population (almost entirely of Aboriginal genetic heritage).

Inferring ethnic origin by means of an STR profile

We report the use of DNA profiles from six STR loci for inferring the ethnic origin of a crime stain and discuss how such inference may be used as intelligence information to reduce the expected number of interviews to resolve a case. To enable this work, databases have been created for five British ethnic groups (Caucasians, Afro-Caribbeans, Indian sub-continentals, Southeast Asians and Middle Easterners) that together comprise 99.7% of the UK population.

A hemizygous short tandem repeat polymorphism 3' to the human phosphoglycerate kinase gene

The human phosphoglycerate kinase (PGK) gene is located within Xq11-Xq13, a region implicated in genitourinary diseases including: prostate cancer, androgen insensitivity, perineal hypospadias, and other genetic abnormalities. The PGK gene and the androgen receptor gene are in linkage disequilibrium. PGK has been mapped extensively for nuclease-sensitive sites, methylation sites, and flanking DNA sequences. A PGK-associated BstXI polymorphism has been used to determine clonality of neoplastic tissues. Using fluorescent PCR product analysis and DNA sequencing, we discovered that a short tandem repeat (STR) in the 3' flanking region of the PGK gene is polymorphic. Among 231 individuals, there were nine distinct alleles, including eight based on variations in the number of TATC repeats. The PGK STR demonstrated hemizygosity, consistent with its X-chromosomal location and with an absence of cross-hybridizing autosomal homologs. The polymorphic PGK STR shows promise for rapid investigation of neoplastic clonality, for personal identification, and for studies of inherited predisposition to urologic disorders.