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Monday, August 17, 2009

Y chomosome Genetic Landscape of the Levant

A new study of Y chromosome haplogroup distribution in the Levant, appearing in the Annals of Human Genetics, establishes a complex pattern of haplogroup distribution, especially with haplogroups J1 and J2, and theorizes on a coastal-inland contrast differentiating J1 and J2 in the Levant. The study included the DNA of 5874 men from the Levant and neighbouring regions, and the results established a coastal-inland, east-west pattern of diversity and frequency distribution within the Levant. The study again shows the most frequent haplogroup in Lebanon is Haplogroup J2, with a frequency of 29.4%. In the South of Syria, in the cities of Damascus and Diraa, J2 was present at frequencies of 24% and 83.3% respectively. In Lebanon, J2 was found in its highest frequencies at Zahle (37.5%) in the Bekaa Valley and at Byblos (36.4%).

Haplogroup J1 was revealed to show a larger frequency but lower diversity in inland regions of the Levant. The authors note most of the interior, where higher frequencies of J1 were found, were arid with semi-desert conditions which support a lower population diversity. Consistent with previous analyses, coastal Levantine regions showed a high frequency of Haplogroup J2.
"The diversified J2 reduced-median network and high coastal frequency suggest a sustained and non-interrupted presence of this haplogroup along the Eastern coast of the Mediterranean"

Geographical Structure of the Y-Chromosomal Genetic Landscape of the Levant: A coastal-inland contrast

Tuesday, August 11, 2009

Jewish priesthood founded on limited paternal lineages

A new study of the Jewish priesthood (Cohanim) suggests the majority of contemporary Jewish priests descend from a limited number of paternal lineages, the 2 largest being in J1e (P58) and J2a (M410). Over 60% of Cohanim descend from one of these 2 paternal lines. Unfortunately the paper did not test for newly discovered SNP's L24 and L25 (rs35248080 and rs34534058), known to be found in a large set of J2 Ashkenazi Cohanim. These haplotypes were simply defined as J2a, M410 in this paper. The study identifies 2 principal founding lineages for Jewish priests, one in J1e (P58) dating back to a common ancestor who lived approximately 3190 years ago and another lineage in J2a (M410) dating back to a common ancestor who lived 4200 years ago. It is also interesting to see a 3rd lineage of Jewish priests from the island of Jerba defined by SNP M318 which also lies downstream of SNP's L24 and L25, also known as J2a4h.

The study was a long overdue followup to a 1997 study which identified a 6 marker Cohen Modal Haplotype. This new paper identifies an expanded 12 marker haplotype in J1 found in a large portion of Cohanim who carry the Y-Chromosome M267 (J1) SNP. The study also showed the likelihood of both the J1e and J2a genetic signatures dating back to before the Jewish diaspora since both signatures were found in Jewish communites from the Near East, Eastern Europe and the Mediterranean, communities which have been, for the most part, separated since roman times.