Ashkenazi Genetic Pile Ups?

Well I thought I had found a real cousin on the German Jewish side due to a few common surnames but no luck finding the relationship yet. Sadly there is a large match on our X but the common surnames are not on a branch where X could come from. Of course one of the problems in German Jewish genealogy is that all but a few prominent families had no fixed surnames (they used their father’s name) until 1813/14.

Even worse she mainly matches me on segments that are what I call “Ashkenazi Pile Ups” or locations where there are well over 30 people matching me but not my Dad for more than 5cm.  By comparison I notice only one such pile up on my 100% Norwegian father’s matches at chromosome 9, at about 80,000. But that will be the topic for another post.

These are the three pile ups my new distant cousin matches:

Chromosome 2:  45 matches for this segment at 23andme

150.1 163.3 9.9CM

Chromosome  4: 80 matches for this segment at 23andme

some start at 18.1 and some end at 25.0

19.4 24.8 7.2CM

Chromosome X: about 30 matches for me, 50 for my brother…. hmmm

a few are longer than this

123.4 137.8 14.1CM

For those of you who are wondering where to find this data on 23andme you can download all the segments that match yours with the name of the donor (most will be anonymous) by going to “ancestry labs” under ‘My Results” and clicking on “Countries of Ancestry.”  Scroll down the page to the long blue button where you can download a CSV of all your matches. [updated 27 dec 2013 – n.b. you can get this data and more  by using the http://DNAgedcom.com site to do the downloads]

There are a few more pile ups in my and my brother’s matches than these …

chromsome 1: 31 matches for this segment

47.0 55.3 7.2

chromsome 1: and 45 matches for this segment

107.9 116.6 11.1

chromosome 2: about 20 or so

16.9 24.5 9.1

to be continued in a future post …. as I find more of these

I googled around and did not find anywhere that listed known ashkenazi genetic segments. Would love to hear if anyone knows more about this. I am sure 23andme has this information as they mark many 3 segment cousins as “distant” so presumably all those segments are known ashkenazi DNA segments.

Edited March 10, 1015 – replaced the incorrect term “hot spot” with the correct term “pile up.” Hot spot has a specific meaning in genetic genealogy which is a place that recombination cross overs happen more often.

5 thoughts on “Ashkenazi Genetic Pile Ups?

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  1. I have since discovered that the term genetic hotspot refers to places where recombination cross overs are frequent so I will have to rename these as persistent DNA segments, PDSs unless there is a better suggestion.

  2. Interesting. I’ve noticed the same phenomenon in FTDNA’s Family Finder results. I have one Jewish 2Ggrandfather. However, the locations where I have the greatest excesses of Jewish matches are different: chromosome 2 at 120963563 to 140029739, chr 10 at 16448878 to 68307817, chr 11 at 59791005 to 90746870, chr 21 at 22255031 to 32136224, X chr at 91045591 to 138635924, and especially chr 9 at 28130215 to 100329812. I was wondering whether anyone had identified characteristically Ashkenazi Jewish segments. But now I’m thinking that what’s characteristic of Ashkenazi ancestry is having certain short segments with whopping numbers of matches to speculative cousins, regardless of where these segments are.

  3. Yes endogamous populations like Ashkenazim do look like that. One researcher told me to ignore ashkenazi matches with no segment of at least 23cM.

    There is a new section under IBD at the ISOGG wiki about pile ups which quotes some of the latest research http://www.isogg.org/wiki/Identical_by_descent#Excess_IBD_sharing

    You can also Check out some of my other articles on Ashkenazi DNA http://blog.kittycooper.com/tag/ashkenazi/

    And hopefully soon I will do another which includes that pile up research

  4. Hi Kitty – This is fascinating. I downloaded my data and sorted to see the pile ups. These segments in my DNA are different than yours, but are in clusters where many of the testers declared Ashkenazi.

    Chr 1, 201 to 209.9. 39 people
    Chr 18, 60.9 to 66.1 24 people

    Also interesting is that none of the 39 on Chr1 are the same as the 24 on Chr18. All unique matches in these separate pileups.

    Thank you for sharing this intriguing info.

    Becka

  5. Becka –
    Yes I am overdue to write a post about pile ups. I corrected my use of the word hot spots above since now there is a term for this: pile ups.

    There is a good section at the ISOGG wiki about pile ups:
    http://www.isogg.org/wiki/Identical_by_descent#Excess_IBD_sharing

    and there is this blog post… Chromosome pile ups in genetic genealogy: examples from 23andMe and FTDNA. Genealogy and Genomics blog, 31 January 2015 at http://ourpuzzlingpast.com/geneblog/2015/01/31/chromosome-pile-ups-in-genetic-genealogy-examples-from-23andme-and-ftdna/

    a fascinating subject
    Kitty

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