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Tuesday, December 23, 2008

Y Chromosomes of Iberia reflect Sephardic and Moorish Origins?

A recent article in the American Journal of Human Genetics, The Genetic Legacy of Religious Diversity and Intolerance: Paternal LIneages of Christians, Jews and Muslims in the Iberian Peninsula attempts to estimate the percentage of Sephardic Jewish and Moorish origins in the present day Iberian population. The results yielded very surprising figures; that upwards of 20% of Iberian Y Chromosomes are of Sephardic Jewish origin and 10% could be of Moorish origin. The history of Iberia certainly records the presence and impact of these 2 cultural groups on the peninsula. This article represents the first attempt using genetics to estimate levels of religious conversion that happened during the Spanish Inquisition period. The study included 1140 DNA samples from Iberia, representing a hugely informative look at the haplogroups of Spain and Portugal as well as long awaited data on the Sephardic Jewish communities mostly originating from Belmonte, Bulgaria, Djerba, and Turkey. The data itself shows that of the 14 haplogroups found in the Sephardic Jewish community, M172, Haplogroup J2 is the most frequent haplogroup overall, representing 25% of this population group. This was followed closely by M267, Haplogroup J1 which represented 22% of the total. In the Iberian Peninsula, M172, Haplogroup J2 was most frequent in the south, 15% in Southern Portugal, 14% in Western Andalusia and 12% in Extremadura. Interestingly, the Balaeric Islands showed lower levels of M172, Haplogroup J2 in Majorca, Minorca and Ibiza at 8, 3 and 4% respectively.

One glaring observation which might challenge the conclusions of the article is the ratio of J:J2 found in the Sephardic Jewish population compared to that of the Iberian population. This ratio is 0.88 (22% vs 25%) in the Separdich Jewish population but only 0.125 (1% vs 8%) in the Iberian Population. If one was to assume the converted Jewish population of Iberia contained a similar genetic makeup to present day Sephardic Jewish communities, looking at Haplogroup J1 as a defining marker, the amount of Sephardic ancestry could not exceed 5% since J1 makes up 22% of present day Sephardic Jews but was found in only 1% of Iberians. From this perspective, the articles conclusions of a 20% Sephardic Jewish ancestry seem lofty. The study's approach was to look at the genetic markers of the Basque population, Moroccan population and present day Sephardic Jewish population to represent Iberian, Moorish and Sephardic ancestry respectively. It then compared this data with that of the 1140 Iberian Y-Chromosomes from the study. Again, the study seems to largely discount the possible input of Phoenician or other near eastern populations as a source for the present day genetic makeup of the Iberian Y chromosome data assuming both Phoenician and Greek impact would be in the eastern parts of Iberia and not in the West where most Haplogroup J2 and J is found. The authors also note a good degree of Haplotype sharing (exact matches) at 3.6% between Sephardic Jewish haplotypes and Iberian Haplotypes. The study also notes the Sephardic sample which is taken from a small group of individuals would have been subject to Founder effect, bottlenecks and other factors which might reduce haplotype diversity.

Looking at the impact of the Moors, the study does provide good evidence linking E3b (M81) to a Moorish population originating in North Africa. The low diversity of this genetic marker comparing North African and Iberian M81 haplotypes supports a very recent common origin, likely brought to Iberia by the Islamic Moors, who controlled the Peninsula for 700 years.

Overall the study does a good job of a very difficult task in attempting to uncover the genetic history of Iberia and how its recent history has had a profound impact on its present day population which undoubtedly includes both Sephardic Jewish and Moorish origins.

Monday, December 15, 2008

Update on rs35248080

The SNP found in Haplogroup J2, rs35248080 should likely split the M410 branch of J2 into 2 large subgroups. Those positive for rs35248080 seem to include all or part of 2 J2 clusters referred to as J2a1h (ISOGG) also known as J2a-Lambda (J2 Y-DNA Project) as well as another cluster, pre-J2a1h (Haplogroup J project) or J2a-Beta (J2 Y-DNA Project). Thus far haplotypes which are M67+ are negative for the SNP rs35248080, haplotypes in J2a that do not carry the deletion at DYS 413 are also negative. Participants in J2b are also negative. Haplotypes which carry a distintive 9 repeats at DYS 450 as well as 6 or 10 repeats at DYS 445 which define J2a1h/J2a-Lambda and pre-J2a1h/J2a-Beta respectively have tested positive for the new SNP. Testing is ongoing.