Very interesting things were found when DNA of Ashkenazi and Sephardi jews, Cohens, Levites and Israelites were compared.

1. DNA pool of all those groups was diverse and contained different haplogroups
2. DNA composition of these groups is similar - more or less same haplogroups, in similar proportions, although there are differences. Except ...
3. DNA of the Ashkenazi Levites is fundamentally different from all other groups. Many Ashkenazi Levites have haplogroup R1a. R1a was very rare among in Sephardi people.

The natural assumption was that this is from the Khazars.
Well, first of all the unknown DNA belongs to the Ashkenazi Khazars, in the second Indo-European haplogroups R1a it occurs, in particular, the eastern Slavs.

Clearly, all this drag-fetched, but the razor Îêêàìà, there is no better explanation.

In addition, 5% (!!!) Ashkenazi Jews belong to haplogroups Q - extended into Siberia, in eastern Asia (in particular Indians are Q1a3).
More - more. Q Jews belong to a rare subgroup Q1b, except those which are (among the studied), only 2 of the tribe on the border of Afghanistan and Pakistan (to some members of these tribes). Q is present, and among the Yemenite Jews, but - Q1a.
Obshy ancestor Ashkenazi Jews Q1b, like many ashkenazskih subkladov lived about 1000 years ago.

My father, incidentally, was of the most Q1b.

When I started the study Q, I soon discovered that not all so simple. Most Q1b - Jews are Ashkenazi, but:
1. There are Jews from Switzerland, who also Q1b, but with a common ancestor with the bulk of which is Ashkenazi Jews 1500-2000 years ago
2. There are non-Jews with Q1b in Europe (admittedly very few), their common ancestor from the Ashkenazi Jews Q1b 2000-2500 years ago. There is a small amount of Q1b and Sephardi.

Explaining all this, when the available data, can be thousands of ways
1. Huns invading Europe in the early 1st millennium could be Q
2.Q1b may be old (ie before the time of scattering) Jewish haplogroups
3. Again Khazars. In favor of this version says that Q1b 5% of the Ashkenazi, but the common ancestor lived about 800-900 years ago. Ie this does not explain the introduction of a single event Q1b Jews. In 1200-1300, when the Ashkenazi was about 25000, Q1b should be about 1000 people. Logically it is closely related to explain Attachments top Khazar Kaganate. Incidentally there is a Hungarian researcher who argues that it was not just Khazars, a kind of royal Ashina.
Ashina came from an area of Mongolia and northern China and were Kaganov with Khazars. At the top they had Kaganate Judaism and, after the fall of Khazar, moved to the west. In the area of Hungary, met with the Ashkenazi. Ostensibly some families are still preserved tradition of the Khazar ancestors. The theory is good. 1000 years ago - the time of the fall Kaganate (approximately). If Ashina come from the east - they were Q. Khazars themselves were more likely R1a (judging by the fact, where they lived) and now it is understandable why the Ashkenazi Levites - Q1b and R1a.
If the royal family, they were many, they had many offspring, and it is clear how they were bottle-neck and is 5%.
4. ... yourself, think of another 997 ideas:)

Certainly do not think that apart from Khazars, nothing to write about DNA genealogy Jews.
Most of the Ashkenazi still belong to the J1, J2, E1b1 - it is a Middle Eastern / Mediterranean haplogroups.


Sources:
Scientific articles:
1. Coffman "A MOSAIC OF PEOPLE: THE JEWISH STORY AND A REASSESSMENT OF THE DNA EVIDENCE" (http://www.jogg.info/11/coffman.htm)
2. Doron M. Behar and others "Contrasting patterns of Y chromosome variation
in Ashkenazi Jewish and host non-Jewish European populations "(http://www.familytreedna.com/pdf/Behar_contrasting.pdf)
3 Doron M. Behar and others Multiple Origins of Ashkenazi Levites: Y Chromosome Evidence for Both Near Eastern and European Ancestries (http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1180600)

Forums and websites
1. Y-DNA haplogroups of ancient civilizations (http://www.eupedia.com/forum/showthread.php?t=25163)
2. Hillel Halkin, Jews and Their DNA (https: / / www.commentarymagazine.com/viewarticle.cfm/jews-and-their-dna-12496?page=all)

FTDNA projects:
1. Ashina Royal Dynasty (http://www.familytreedna.com/public/AshinaRoyalDynasty/default.aspx) Contains long description, why jewish Q are related to Ashina.
2. Jewish DNA Project (http://www.familytreedna.com/public/JewishDNAProject/default.aspx)