Interesting-sounding posters from 2009 ASHG meeting

Titles only -- abstracts aren't up (via Polak):
Accurate inference of individual ancestry geographic coordinates within Europe using small panels of genetic markers. P. Paschou, J. Lewis, P. Drineas.

Super Y-chromosomes in Eurasia and the impact of social selection and Neolithic transition. P. L. Balaresque, E. Heyer, M. A. Jobling.

Admixture between Ashkenazi Jews and Central Europeans. W. Klitz, L. Gragert, M. Maiers, M. Fernandez-ViƱa, Y. Ben-Naeh, G. Benedek, C. Brautbar, S. Israel.

Patterns of correlation between genetic ancestry and facial features suggest selection on females is driving differentiation. D. K. Liberton, K. A. Matthes, R. Pereira, T. Frudakis, D. A. Puts, M. D. Shriver.

Fine-scale Population Structure in Worldwide Ethnic Populations as Revealed by Identical by Descent Segments. B. M. Henn, L. Hon, J. M. Macpherson, N. Eriksson, A. Wojcicki, L. Avey, S. Saxonov, J. L. Mountain.
I doubt that 23andMe's presentation (last entry above) simply "pertains to the methodology behind their company's Ancestry Painting tool", as Polak speculates. Sounds like something more interesting. Update: I'm right. The abstract has been posted at 23andMe.

Fine-scale Population Structure in Worldwide Ethnic Populations as Revealed by Identity by Descent Segments

Brenna M. Henn1, Lawrence Hon1, JM Macpherson1, Nick Eriksson1, Anne Wojcicki1, Linda Avey1, Serge Saxonov1, Joanna L. Mountain1*

It is well established that human population genetic diversity reflects continental-level geographic divisions, and that within-continental geographic and linguistic differences contribute to population structure between regions. The continental and regional differences reflect ancient demographic events, such as early migrations Out of Africa into Eurasia. However, it is not clear how recent demographic processes occurring on the order of hundreds, rather than thousands, of years affect patterns of genomic diversity. We analyzed the sharing of DNA identical by descent (IBD) inferred from 580,000 SNPs using a large database of individuals with European ancestry, including a subset identifying as Ashkenazim. We also explored the pairwise distributions of identical by descent segments in populations from the Human Genome Diversity Panel (HGDP-CEPH), a diverse set of ethnic groups from across the world. We observed that the average number and sizes of shared genomic segments differ substantially across the ~55 populations. The different patterns are likely attributable to differences in population histories such as recent bottlenecks and sub-structure. In particular, populations that are highly structured will contain individuals that share elevated amounts of IBD, indicative of recent common ancestry through multiple ancestors. In order to understand the pattern of the observed population-level sharing, we simulated extended pedigrees using empirical data from several populations and calculated the expected amounts of sharing for 1st through 10th cousins. We assumed random mating within each population for the simulations. Interestingly, the average sharing in the simulated distant cousins was consistently less than the observed average sharing in each population sample. This finding indicates the presence of fine-scale population structure for many ethnic groups, such as the Ashkenazim, within the last 10 generations (200-300 years).

No comments: