Investigation of X-STR haplotype diversity in the Australian Aboriginal population

X-chromosome short tandem repeat (X-STR) analysis complements autosomal and Y-chromosome STR typing for complex kinship analysis and screening of candidate lists in familial searches. To statistically evaluate X-STR profiling results, Australian forensic laboratories require X-STR haplotype frequency databases for relevant populations. Our study is the first to report haplotype data for the Australian Aboriginal population. X-STR haplotypes were generated for 298 self-declared male Aboriginals using the Investigator® Argus X-12 Kit. Haplotype frequencies and parameters of forensic interest are presented. The discrimination power of a full haplotype was 98.7% and the cumulative power of discrimination was 0.9999999988 for males and 0.999999999999999 for females. MDS plots of pairwise F_ST genetic distances and STRUCTURE histograms identified some segregation of X-STR haplotypes between individuals from the Desert and Eyre regions as compared to the Spencer, Riverine and urban Adelaide regions. Comparison of Australian Aboriginal X-STR haplotypes to those of other global populations showed the most similarity to Europeans and least similarity with Asian populations. Ancestral X-STR haplotypes appeared most conserved in the outback Desert and Eyre regions where assimilation with Europeans is lower. Overall genetic structure was minimal and a single X-STR haplotype database combining all regions is considered appropriate for likelihood ratio calculation.