Abstract for presentation at 11th International Congress of Human Genetics

Sequence variation in the mitochondrial ATP6, ND3 and CytB loci in Aboriginal Australians

  • Ms Pei Yan Liu, School of Biotechnology and Biomolecular Sciences, University of New South Wales., Australia
  • Dr Sheila van Holst Pellekaan, School of Biotechnology and Biomolecular Sciences, University of New South Wales., Australia
  • Dr Alan Wilton, School of Biotechnology and Biomolecular Sciences, University of New South Wales., Australia
  • Mr Pat Iversen, AVI BioPharma, Corvallis, Oregon, USA, United States
  • A/Prof Steve Wilton, Australian Neuromuscular Reasearch Institute, Australia

    • Human mitochondrial (mtDNA) has been widely used to investigate population history. Most studies assume that variation in mtDNA is selectively neutral and mutation rate is constant. However, some studies have suggested departure from neutrality. The issue of whether or not human mtDNA variation fits the neutral model has been investigated in this study. Sequences of the ATP6, ND3 and CYTB genes were determined in the mtDNA of Aboriginal Australians from western New South Wales and central Australia. Five synonymous (s) and 15 nonsynonymous (ns) substitutions were identified in the ATP6 locus, 2s and 2ns in ND3 and a total of 13s and 14ns substitutions were identified in CYTB. These polymorphisms and those in 20 published sequences of Australians from the Northern Territory (Ingman and Gyllensten 2003) were then investigated for consistency with a neutral model of molecular evolution by applying various neutrality tests. The sequences were firstly analysed by division into geographical regions (Riverine, Desert and Northern Territory) and secondly into haplogroups determined from full genome sequences (van Holst Pellekaan et al, in press). Departure from neutrality was observed in some tests but not in others. However, there were a few notable observations: i.e. departure from neutrality was seen in both the ATP6 and CYTB sequences in the Northern Territory region and in the total sequence data set. For the CYTB sequences in the Riverine region, haplogroups AuB and AuC revealed an excess of ns fixed differences between human and mouse, an observation that is inconsistent with the neutral equilibrium model. We are unable to explain these observations in terms of selection because not all neutrality test results agreed. In addition, the Tajima’s D statistic was significantly negative for the ATP6 sequences in haplogroup AuC, population expansion possibly explaining this result. The results of this project do not support nor reject the neutral model of mtDNA evolution.

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