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Lookup NU author(s): Dr Ian Wilson
Background. We reasoned that by identifying genetic markers on human X chromosome regions where recombination is rare or absent, we should be able to construct X chromosome genealogies analogous to those based on Y chromosome and mitochondrial DNA polymorphisms, with the advantage of providing information about both male and female components of the population. Methodolgy/Principal Findings, We identified a 47 Kb interval containing an Alu insertion polymorphism (DXS225) and four microsatellites in complete linkdge disequilibrium in a low recombination rate region of the long arm of the human X chromosome. This haplotype block was studied in 667 males from the HGDP-CEPH Human Genome Diversity, Panel. The haplotypic diversity was highest in Africa (0.992 ± 0.0025) and lowest in the Americas (0.839±0.0378), where no insertion alleles of DXS225 were observed. Africa shared few haplotypes with other geographical areas, while those exhibited significant sharing among themselves. Median joining networks revealed that the African haplotypes were numerous, occupied the periphery of the graph and had low frequency, whereas those from the other continents were few, central and had high frequency. Altogether, our data support a single origin of modern man in Africa and migration to occupy the other continents by serial founder effects. Coalescent analysis permitted estimation of the time of the most recent common ancestor as 182,000 yeats (56,700-479,000) and the estimated time of the DXS225 Alu insertion of 94,400 years (24,310,000), These dates are fully compatible with the current widely accepted scenario of the origin of modern mankind in Africa within the last 95,000 years and migration out-of-africa circa 55,000-65,000 years ago. Conclusion/Significance. A haplotypic block combining an Alu insertion polymorphism and four microsatellite markers on the human X chromosome is a useful marker to evaluate genetic diversity of human populations and provides a highly informative tool for evolutionary studies. © 2007 Santos-Lopes et al.
Author(s): Santos-Lopes SS, Pereira RW, Wilson IJ, Pena SDJ
Publication type: Article
Publication status: Published
Journal: PLoS ONE
Year: 2007
Volume: 2
Issue: 6
Date deposited: 04/02/2010
ISSN (electronic): 1932-6203
Publisher: Public Library of Science
URL: http://dx.doi.org/10.1371/journal.pone.0000557
DOI: 10.1371/journal.pone.0000557
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