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Friday, July 20, 2012

Ancient Migratory Events in the Middle East-Y Chromosome Variation of Iranians

A very comprehensive new study on Y-Chromosomes in Iran is shedding light on Haplogroup J2 and the origins of its subclade, M530, also known as L24 and defined by the SNP rs35248080.  The study looks at various population groups in Iran and the spread of Y-Chromosomes.  From a J2 persective, M410, L26, M530 (L24), M67 and M92 were studied along with M205 and M241 in Haplogroup J2b.  The results showed an ancient background mainly composed of J2a subclades, along with an influx of M92 from Asia Minor into certain groups in Iran.  Overall Haplogroup J comprised 31.4% of all modern Iranians combined; with J2 making up 22.5% of the population, the overwhelming majority of that being M410+ (J2a).  From the paper:
In particular, the recently described J2a-M530 shows high frequencies in the Zoroastrians of Yazd (17.6%) and Tehran (15.4%), and in Persians of Yazd (17%).  J2a-M47 reaches frequencies higher than 5% in Yazd, Mazandaran, Khuzestan and Fars....Among the different J2a haplogroups, M530 is the most informative as for ancient dispersal events from the Iranian region.  This lineage probably originated in Iran where it displays its highest frequency and variance in Yazd and Mazandaran.

Also of interest in the paper, some ancient deep rooted lineages from IJ-M429 were observed in the Iranian Plateau.  This of course, forms a solid foundation for the theory of the spread of humans from Iran over the course of history into both India, other parts of the Middle East and elsewhere in Europe.  M530 however, showed a curious diffusion from a fairly clear origin in Iran.  While it did spread early to Turkey and the Levant where subcaldes Z387 and L70 (distinguished in part by DYS 391=9) likely arose, the authors report an almost complete absence of M530 from Iraq in table S3 (only 1.3% in Baghdad, 0% in Marsh Arabs).  It is also absent from 4 of 11 regions referenced from Turkey/Asia Minor and almost completely absent from many areas of Europe with the exception of Italy where migrations of M530 subclades Z387+ and L70+ from Anatolia likely occurred.  Was this uneven distribution through the near east the result of  climate, topography or other civilizations?  The paper does not address this issue and the age estimates and theorized spread discussed in the paper do not seem to correlate with the uneven results reported.  Nevertheless, the paper provides invaluable data on Iran; it is the second major paper to address J2a-M530 and provides a window into theY-chromosome makeup of modern day Iran with genetic clues to a very ancient presence of Humans in the country.