PMC:2427286 / 14848-19174 JSONTXT

{"project":"2_test","denotations":[{"id":"18374297-17275346-2052371","span":{"begin":714,"end":716},"obj":"17275346"}],"text":"Identification of Potential Sources for Lebanese Genetic Structure\nBecause religious affiliation has the greatest impact on the patterns of genetic variation in Lebanese populations, and because these religions have originated within historical times, we first sought explanations for the genetic differences from the documented historical migrations: Muslim, Crusader, and Ottoman (Figure 1). Using historical evidence, we identified source regions for these migrations in the Arabian Peninsula, western Europe, and Turkey, respectively. We then collected suitable Y-chromosomal SNP datasets from these areas. For the Arabian Peninsula and Turkey this was simple, and data from France, Germany, England, and Italy15 were used to construct a suitable western European sample as described in the Material and Methods section. Because we needed to compare the Lebanese data with the same haplogroups in these additional datasets, we combined some related haplogroups to form eight haplogroups [E3b, G, I, J∗(xJ2), J2, K2, L, and R1b] that were each present in Lebanon at \u003e 4%, together accounted for 90% of the Lebanese sample, and could be compared with the categories used by other authors (Table 5).\nA standard approach to determining whether migration from these countries might have contributed to the Lebanese population would be to perform an admixture analysis with the putative source as one parental population. Taking such an approach, we could identify possible contributions from the Arabian Peninsula to Lebanese Muslims and from western Europe to Lebanese Christians, but the uncertainties in the estimates were large, and no meaningful result was obtained when Turkey was used as a potential source (Table 6). In order to investigate further, we then compared individual haplogroup frequencies in Lebanon and the putative source regions, and we identified haplogroups that differed significantly in frequency by using a Chi-square test with a Bonferroni correction for multiple testing. A number of haplogroups were found at significantly higher frequency in the potential source region than in Lebanon: J∗(xJ2) in the Arabian Peninsula, I and R1b in the western European sample, and R1b in Turkey (Table 5). Because the extent to which the western European sample used here might represent the Crusaders is uncertain, we investigated the sensitivity of our conclusion to the composition of this sample. Haplogroups I and R1b were both present at higher frequency in each of the individual populations, and the difference was significant for R1b in all four populations and for I in two of them (Germans and English). No other haplogroup was at a significantly higher frequency in any of the individual populations than in Lebanon. We therefore conclude that this is a robust finding.\nThese observations, together with the historical information, led us to formulate three specific hypotheses: that many J∗(xJ2) chromosomes were introduced into Lebanese Muslims by the Muslim expansion from the Arabian Peninsula; that some I and R1b chromosomes were introduced into Lebanese Christians by immigrating European Christians, perhaps during the time of the Crusades; and that additional R1b chromosomes were introduced into Lebanese Muslims during the Ottoman expansion. We do not, of course, imply that these migrations carried only these haplogroups; obviously, they would have involved populations containing multiple haplogroups. The signal of migration, however, should be most readily detected in the highly differentiated haplogroups. J∗(xJ2) was found to be much more frequent in Lebanese Muslims than in Lebanese non-Muslims (25% vs. 15%, p \u003c 0.0001). The combined I + R1b frequency was higher in Lebanese Christians than in Lebanese non-Christians (16% vs. 10%, p = 0.01), as were both of the individual haplogroups (I: 5.8% vs. 4.0%, p = 0.21; R1b 10% vs. 6.3%, p = 0.03), although the difference for haplogroup I alone did not reach statistical significance. The R1b frequency was, however, significantly lower in Lebanese Muslims than in Lebanese non-Muslims (4.7% vs. 11%, p = 0.0005). The hypotheses of male-mediated gene flow accompanying the earlier Muslim and Crusader migrations are therefore supported, but our data provide no evidence for a differential genetic impact of the Ottoman expansion."}