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Referee Comments: Referee 2

Posted by PLOS_ONE_Group on 13 May 2008 at 23:52 GMT

Referee 2's Review:

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N.B. These are the comments made by the referee when reviewing an earlier version of this paper. Prior to publication, the manuscript has been revised in light of these comments and to address other editorial requirements.
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The manuscript entitled « The Druze: A Population Genetic Refugium of the Near East » by Shlush et al. presents a survey of mtDNA and Y-chromosome diversity in a very well-defined sample of Druze from diverse locations. The main result of this paper is that high frequencies and high diversity of mtDNA haplogroup X are observed. The authors conclude that this observation testifies for the Druze as representing a snapshot of the genetic landscape of the Middle East in more ancient times.

The paper is very well written and the conclusions are quite supported by the data. Moreover, I think that the sampling strategy used in exemplary. My only concern is that, although the authors have analyzed both Y-chromosome and mtDNA diversity, no mention of the Y-chromosome results is given in the main body of the text (just supplementary material). I strongly encourage the authors to at least write a paragraph giving the general observations of the Y-chromosome diversity both contrasting these results with those from mtDNA and in the more general context of the Y-chromosome diversity of the Middle East.