Little or no gene flow gene flow found between ashkenazi jews and non jews in russia & poland. Also Ashkenazi Jews, considered to be an isolated population that has undergone a recent bottleneck constitute a model population for the search of disease-causing mutations & disease-susceptibility genes
(booksc.org)https://booksc.org/book/10736801/6d3125Full source
To test for possible admixture between Ashkenazi communities and local non-Jewish populations, we
used a log-linear model8 to compare mtDNA haplogroup
distribution of the Jewish RU and Polish groups to the
available data on the haplogroup distribution of nonJewish RU and Polish populations, respectively10 (Table 2).
This analysis revealed a significant divergence in total
haplogroup distribution between the Ashkenazi Jewish and
the local populations (ethnic background haplogroup
interaction term, G ¼ 173, df ¼ 8, Po0.001). A nonsignificant three-way interaction term (G ¼ 7.7, df ¼ 8, P ¼ 0.463)
reflects that the differences between Jews and non-Jews was
consistent both in the RU and Polish populations. These
findings, taken together with HVR1 sequences for some
of the haplogroups, such as N1b, that contain motifs
restricted and common to all Ashkenazi Jewish populations,1 may further support the interpretation of little or
no gene flow of the local non-Jewish communities in
Poland and Russia to the Jewish communities in these
countries
