NEW YORK (GenomeWeb News) – Jewish populations in North Africa carry genetic patterns that correspond to some extent with those found in Jewish populations from other parts of the world, according to a study in the early, online edition of the Proceedings of the National Academy of Sciences this week.
"Our new findings define North African Jews, complete the overall population structure for the various groups of the Jewish Diaspora, and enhance the case for a biological basis for Jewishness," senior author Harry Ostrer, a pathology, genetics, and pediatrics researcher at Albert Einstein College of Medicine, said in a statement.
Ostrer and colleagues from the US, Israel, Spain, and France genotyped individuals from five Jewish populations in North Africa as well as Jewish populations in Georgia, Ethiopia, and Yemen. They then compared SNP patterns in these populations with those found in non-Jewish North African populations and in Jewish populations from other parts of the world.
Although individuals in the North African Jewish populations carried North African ancestry, Middle Eastern ancestry, and varying degrees of European ancestry, these populations generally clustered with Jewish populations in other parts of the world rather than with other North African populations. In addition, the team found that relationships between specific populations often corresponded to historical migrations and events within the region.
"[T]his study is compatible with the history of North African Jews — founding during Classical Antiquity with proselytism of local populations, followed by genetic isolation with the rise of Christianity and then Islam, and admixture following the emigration of Sephardic Jews during the Inquisition," study authors explained.
The new work represents the latest genetic effort to untangle relationships within and between Jewish populations — and to retrace Jewish population migrations from the Middle East to various parts of the world over thousands of years, collectively called the Jewish Diaspora.
For example, a 2010 study in the American Journal of Human Genetics by Ostrer and his colleagues indicated that individuals from present-day Sephardic, Ashkenazi, and Mizrahi Jewish populations share some genetic features, but also cluster into sub-groups that reflect past migrations and, in some cases, mixing with European populations.
Another team of researchers from Israel, Estonia, and elsewhere provided its own look at the genetic patterns within Jewish populations in Nature in 2010 — an analysis that traced modern Jewish populations back to the eastern Mediterranean/Middle Eastern region known as the Levant.
For the new study, researchers used Affymetrix 6.0 arrays to profile genetic variant patterns in samples from more than 500 Jewish individuals representing 15 populations. Among them: Jewish populations from Morocco, Algeria, Tunisia, Libya, Ethiopia, Yemen, Georgia, and Djerba, an island found off of Tunisia's southeastern coast.
They then compared patterns in these samples with new genotyping data for 114 individuals from seven neighboring, non-Jewish populations, along with existing data for another 365 individuals who had been assessed with Illumina HumanHap 650K beadchip arrays as part of the Human Genome Diversity Project.
The researchers' analyses suggest that Jewish populations in North Africa fall into a group that can be distinguished genetically from non-Jewish populations in the region — a cluster that roughly overlapped with Middle Eastern and European Jewish populations.
Within the North African Jewish populations, the team also defined two broad sub-groups: the Moroccan-Algerian group, which is more closely related to European Jewish populations, and the Djerban, Libyan, and Tunisian group, comprised of populations that have remained closely related to one another.
Within these groups, the team defined finer scale relationships between populations that, in some cases, appeared to stem from known historical events.
In addition to finding more pronounced European ancestry in Jewish populations in western parts of North Africa such as Morocco and Algeria, for instance, the researchers noted that these populations clustered particularly close to Sephardic Jewish populations from Greece, Turkey, and Italy — a pattern that the study authors attributed to Jewish population movement out of Spain in the 1490s during the Spanish Inquisition.
"These results are in agreement with previous population genetic studies of North African Jews," study authors noted, "yet significantly expand their observations by using larger numbers of populations and contemporary methods."