The Y chromosome pool of Jews as part of the genetic landscape of the Middle East

Abstract

A sample of 526 Y chromosomes representing six Middle Eastern populations (Ashkenazi, Sephardic, and Kurdish Jews from Israel; Muslim Kurds; Muslim Arabs from Israel and the Palestinian Authority Area; and Bedouin from the Negev) was analyzed for 13 binary polymorphisms and six microsatellite loci. The investigation of the genetic relationship among three Jewish communities revealed that Kurdish and Sephardic Jews were indistinguishable from one another, whereas both differed slightly, yet significantly, from Ashkenazi Jews. The differences among Ashkenazim may be a result of low-level gene flow from European populations and/or genetic drift during isolation. Admixture between Kurdish Jews and their former Muslim host population in Kurdistan appeared to be negligible. In comparison with data available from other relevant populations in the region, Jews were found to be more closely related to groups in the north of the Fertile Crescent (Kurds, Turks, and Armenians) than to their Arab neighbors. The two haplogroups Eu 9 and Eu 10 constitute a major part of the Y chromosome pool in the analyzed sample. Our data suggest that Eu 9 originated in the northern part, and Eu 10 in the southern part of the Fertile Crescent. Genetic dating yielded estimates of the expansion of both haplogroups that cover the Neolithic period in the region. Palestinian Arabs and Bedouin differed from the other Middle Eastern populations studied here, mainly in specific high-frequency Eu 10 haplotypes not found in the non-Arab groups. These chromosomes might have been introduced through migrations from the Arabian Peninsula during the last two millennia. The present study contributes to the elucidation of the complex demographic history that shaped the present-day genetic landscape in the region.

Figure 1

Network of Y chromosome haplogroups (Hgs) based on the 13 binary polymorphisms analyzed. Unblackened circles represent haplogroups observed in the six Middle Eastern populations. The area of each circle is proportional to the frequency of the haplogroup in the total sample. Small blackened circles denote unobserved haplogroups. Arrows indicate the direction of the defining mutation. The haplogroup classification follows Rosser et al. (2000), except for the “Eu” designations, which are classified according to Semino et al. (2000). Hg 7 is the root. Eu 10 and Eu 9 are sublineages of Hg 9 that are distinguished by the mutation at M172. Hg 3 and Eu 19 appear phylogenetically equivalent in our sample. Hg 3 is defined by the reverse mutation at SRY10831 and Eu 19 by the polymorphism at M17.

Figure 2

Unrooted NJ tree depicting relationships among the six Middle Eastern populations, based on D_A distances. The distance matrix is calculated using frequencies of haplogroups defined by 13 binary Y chromosome polymorphisms.

Figure 3

Simplified network relating the five modal haplotypes found in the six Middle Eastern populations. The haplotypes are defined by alleles at six microsatellite loci in the order DYS19, DYS388, DYS390, DYS391, DYS392, and DYS393. Lines between the haplotypes represent single-microsatellite mutation steps. The frequency of the modal haplotypes in each population is shown. AJ = Ashkenazi Jews; SJ = Sephardic Jews; KJ = Kurdish Jews; PA = Palestinian Arabs; B = Bedouin; MK = Muslim Kurds; MH = modal haplotype; and CMH = Cohen modal haplotype. Note that the CMH and the MH of the Muslim Kurds are only one microsatellite mutation step apart but occur on different haplogroup backgrounds (Eu 10 and Eu 9, respectively).

Figure 4

Unrooted NJ tree depicting relationships among 18 populations based on D_A. The distance matrix is calculated using frequencies of haplogroups defined by nine binary Y chromosome polymorphisms.

Figure 5

MJ network of Eu 10. The network shows the genealogical relationships of the 47 microsatellite haplotypes found in 133 Eu 10 Y chromosomes from six Middle Eastern populations. The areas of the circles are proportional to the haplotype frequencies. Branch lengths are proportional to the number of mutational steps, and parallel links in a reticulation represent the same mutational changes. “Median vector” stands for a presumed haplotype not observed in the sample. The various populations are represented by different colors, as designated. The number next to the circle refers to the haplotype number in the Appendix. Haplotype 159, at the center of the network, is the CMH. The Arab clade haplotypes that have been defined elsewhere are underlined.

Figure 6

Geographical distribution of Eu 9 and Eu 10. The haplogroups are represented by different shades of grey as designated. The number in each pie indicates the population analyzed. The data are from Semino et al. (2000) for the following populations: 1 = Sardinians; 2 = central-northern Italians; 3 = Calabrians; 4 = Greeks; 5 = Macedonians; 6 = Ukrainians; 7 = Turks; 8 = Lebanese; 10 = Syrians; and 12 = Georgians. Data from the present study are from the following populations: 9 = Jews; 11 = Palestinian Arabs; and 13 = Muslim Kurds.