Nuclear DNA diversity in worldwide distributed human populations

Ewa Ziȩtkiewicz, University of Montreal
Vania Yotova, University of Montreal
Michal Jarnik, University of Montreal
Maria Korab-Laskowska, University of Montreal
Kenneth K. Kidd, Yale School of Medicine
David Modiano, Università degli Studi di Roma La Sapienza
Rosaria Scozzari, Università degli Studi di Roma La Sapienza
Mark Stoneking, Pennsylvania State University
Sarah Tishkoff, Yale School of Medicine
Mark Batzer, University Medical Center New Orleans
Damian Labuda, University of Montreal


Nucleotide variation was examined in an 8 kb intronic DNA bordering exon 44 of the human dystrophin gene on Xp21. Thirty-six polymorphisms (substitutions, small insertions/deletions and one (T)(n) microsatellite) were found using SSCP/heteroduplex analysis of DNA samples from mixed Europeans, Papua New Guineans as well as from six African, three Asian and two Amerindian populations. In this way the European bias in the nuclear polymorphism ascertainment has been avoided. In a maximum likelihood tree constructed from the frequency data, Africans clustered separately from the non-African populations. Fifteen polymorphisms were shared among most of the populations compared, whereas 13 sites were found to be endemic to Africans and four to non-Africans. The common sites contributed most to the average heterozygosity (H(n) = 0.101% ± 0.023), whereas the endemic ones, being rare, had little effect on this estimate. The F(ST) values were lower for Africans (0.072) than for non-Africans (0.158), suggesting a higher level of gene exchange within Africa, corroborating the observation of a greater number of segregating sites on this continent than elsewhere. The data suggest a recent common origin of the African and non-African populations, where a greater geographical isolation of the latter resulted in a smaller number of newly acquired polymorphisms.