Ashkenazi Jews are one group that fall under the umbrella of “European”, but it’s clear from numerous studies that they’re genetically unique and distinct from the European population at large. Most people with Ashkenazi ancestry trace their DNA to Eastern and Central Europe, but also have Middle Eastern ancestry, which is just one reason for their genetic “uniqueness”.
Genetic Variation Between and Within Populations
It’s clear that people with European ancestry are genetically distinct from those of Asian or African descent, but what’s less obvious is that genetic variation also exists within European groups. In these plots from a study by Elimear Kenny, you can see the genetic variation between major ancestral groups (left) and within a population (right). Jewish groups fall into the European cluster on the left, but people with Ashkenazi ancestry (blue) form a unique cluster that is largely distinct from Caucasian (CEU; green) and other Jewish populations (various colors) on the right. Individuals who are part Ashkenazi fall in between the Caucasian and Ashkenazi clusters.
The challenging history of Jewish groups has also contributed to their genetic uniqueness. During the Jewish Diaspora — or migration of Jewish people from the Middle East to other parts of the world — the vast majority of Jewish individuals married and raised families within their faith. Many generations later this means that Ashkenazi Jews can appear more genetically related than they actually are.
This genetic isolation has had important implications for health. People with Ashkenazi ancestry are more likely to carry genetic factors that cause single-gene recessive Mendelian disorders where you need two bad copies of a gene to get the disease. Examples include Gaucher disease, Canavan disease, and Tay-Sachs disease. Because of this higher likelihood, screening for these genetic variants in prospective parents is standard practice for Jewish individuals starting families.
(23andMe tests for most mutations routinely screened in the Ashkenazi Jewish population for these conditions).
23andMe customers can learn about their ancestry and view their results for Gaucher disease, Canavan disease, and Tay-Sachs disease in their account.
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A number of multi-gene conditions (or those caused by genetic variation in a handful of genes) are also more common in people with Ashkenazi ancestry. One example is Crohn’s disease, which people with Ashkenazi ancestry are two to four times as likely to develop compared Europeans in general. Although it’s not yet clear why the rates are higher in this population, it’s likely that genetic factors specific to individuals with Ashkenazi ancestry play a role.
Knowing about your ancestry can teach you about your family’s heritage and your risk for disease — and more knowledge means more informed decisions.
May is Jewish American Heritage Month. Check back later to read about genetic risk factors for Crohn’s disease that appear to be specific to people with Ashkenazi Jewish ancestry. You can also read about uncovering Jewish ancestry in guest posts by 23andMe’s Ancestry Ambassadors, Tim Janzen, CeCe Moore and Andrea Badger.
The French Canadians are unique too, with small founder population effects and increased incidences of certain genetic diseases.
Hello Martin,
Thanks for your comment. I totally agree that French Canadians are very unique, too and recently blogged about it. Check it out if you haven’t already: http://spittoon.23andme.com/announcements/french-canadian-ancestry-and-relevant-health-conditions/
Hi,
On the Robert Downey Jr. episode of Finding Your Roots, Henry Louis Gates told him that he was 21% middle eastern. Is your DNA able to tell me what percent middle eastern I am? I am an Ashkenazi Jew, and in the summer when I’m tanned or whenever I have a thick beard, I look extremely middle eastern, though my roots as far back as I can tell are Russian, Ukrainian, Polish and Hungarian.
Thanks,
Craig
recent studs show that Ashkenazi does not come from Khazar they actually come from middle eastern people far back in the day .
Why the bias and concentration on research towards a religious group? Jews are from all around the globe. Ashkenazis are mixed beyond recognition. Khazaria is the only logical candidate for an origin of a majority of ‘Jews’. Not Palestine or the ‘levant’.
My comment has little to do with Ashkenazi Jews or the “Caucasians”, the Americans chosen as representing Europe and Europeans. My comment concerned ascertainment bias. In the first pictorial, only three groups representing Africa, East Eurasia, and West Eurasia were chosen. Of course a clear cut separation would ensure, there were no East Africans, North Africans, Europeans from Europe, Near Eastern populations or the various populations of Asia other than the Chinese and Japanese. It is biased. If all populations were included there would be no clear cut separation. As for the second pictorial, the exclusion of Europeans from Europe especially the Southern Europeans from Italy, Albania, Greece and West Asian populations like Cypriots, Anatolian Turks, Levantine Near Easterners contributed to that biased and misleading pictorial. The fact is many Southern Europeans, Anatolian Turks and Cypriots would be in exactly the same spots as many of those Jews.
Rather than make assumptions about European Jews as in accepting their Near East origins due to diasporia events, it would be better to try to find out where exactly European Jews, the Sephardi and the Ashkenazi Jews, hailed from. At present it looks like those Jews are not Near Eastern but either Southern Europeans or from Anatolia. I prefer truth to junkets.
You are basically cherry-picking populations to prove a point. Why not include South Europeans? Do you only consider Anglo-Protestants to be “Caucasians”, whatever that is supposed to mean (people from the Caucasus region?) I expect more from 23andMe than this pseudo-scientific nonsense.
Hi mistral,
May is Jewish American Heritage month and this post is one of two we’ll be posting on the blog on the topic of Jewish ancestry. The genetic characteristics of this population were recently highlighted in the study mentioned in the post. As another commenter pointed out, other populations certainly also have their own unique genetic characteristics and their own unique health implications. The diversity of human genetics and what it can tell us about human history, health and traits is certainly amazing. Thanks for reading!
Hi BethannH,
What are the values of the x and y axes in the graph? I know they are labeled if you look in the paper but I don’t really know what the labels mean (PC2 and PC1?). Can you explain what information is actually contained in the graph?
Michael
Hi Michael,
The researchers used Principal Components Analysis (PCA) to generate these graphs and PC1 and PC2 are just short for “principal component 1″ and “principal component 2″. PCA is used to reduce the dimensionality of a data set and can reveal the sometimes hidden structures in data sets. In this instance, the researchers compared DNA from 3,252 study participants to DNA from different reference population samples, for instance Chinese (CHB), Japanese (JPT), Yoruban (YRI) and a variety of Caucasian (CEU) samples. (These reference population samples are freely available and were originally generated by the International HapMap project: http://hapmap.ncbi.nlm.nih.gov/hapmappopulations.html.en). PCA allowed the researchers to see how similar the DNA was between the study participants and the reference populations for which the ancestry was already defined.
The researchers explain in the paper that in the left plot, “PC1 distinguishes Africans from non-Africans and PC2 distinguishes East Asians from Africans and individuals of European and Jewish ancestry”. For the right plot, “PC1 distinguished European from Jewish ancestry and PC2 shows a Middle Eastern to European cline of Jewish populations, with the majority of AJ individuals (~80%) clustering distinctly from other European Jewish populations.”
I am surprised that this article claims that most Ashkenazi Jews trace their DNA to Central and eastern Europe. In fact, they do not. More recent advances show them to be largely, not just partly Middle eastern, Their European DNA appears to come largely from Southern Europe, namely Italy. Apart from the existence of low level EU 19 haplogroups, their links to eastern Europe are remote indeed.
Part of this depends on the time frames we’re talking about. While going back far enough you may indeed trace Ashkenazi Jewish ancestry to the Middle East, the reason their ancestry is so distinctive is because of the bottleneck of history that concentrated this population in geographic areas in Eastern Europe.
Ashkenazim Jews in many cases are labeled part middle eastern genetically.I would like to point out that Ashkenazi Jews are part ANCIENT leventine genetically. Don’t confuse the modern browning of the levant that started with Mohammad;s southern Arabian invasions centuries after the diaspora of the jews.The leventine Jewish peoples 2000 years ago were Caucasians very similar genetically to southern Europeans.The middle east today is racially completely different then when the jews left it 2000 years ago.Ashkenazi Jews are in a nutshell southern Europeans with some eastern and northern European DNA.The brown Arabs are NOT native to the levant and they are not related to the jews.There are many white native levantine arabs in Lebanon and Jordan plus Syria and they look like Frenchmen and that’s what the Ashkenazi jews looked like 2000 years ago.
I am an Ashkenazi Jew who had his DNA tested. Both sides of my family came from Germany. The results showed my DNA to be 100% Middle Eastern, 79% Jewish and 21% Palestinian or Bedouin. In other words 21% of my DNA is shared also by the modern-day population which calls itself “Palestinian”, indicating we had common ancestors in ancient times; I would guess Canaanites. My “cousins” are all Jewish or people who had a Jewish ancestor. It will be interesting when Levatine Arabs join the database to see if I find “cousins” listed from that group.
I do agree with the previous poster, though, that the Levantine population acquired non-Levantine DNA centuries after the Jews were driven out. Modern-day Levantine Arabs have significant sub-Saharan African and South Asian DNA, especially Muslim Arabs. They also have a DNA heritage of the ancient Levant, just as the Jews do. In that respect Jews and Levantine Arabs are genetically related.
My paternal Halogroup i,from my father Woodson Bell Harvell on Ancestry.com,is East African,European and Scandanavian,Irish,and Scotland,we also have Jewish and Asian ancestry.My maternal Halogroup from my mother is also East Africa ,Irish,European,and Jewish,her ancestors more than likely were in Egypt with the Jews.Our ancestry is very rich in history.
My brother William Donald Harvell provided the paternal DNA for our father Woodson Bell Harvell on Ancestry.com in my account,which shows our ancestry in detail,which shows our African,European and Scandanavian roots.
I am an Ashkenazi and look caucasian german polish mix with a caucasian georgian French Bourbon nose with an horizontal nose base bleu eyes blond hair slim tall like northern and have only european genome and NONE of all variants of the famous Page of diseases which are so frequent among near sic centuries endogamic Ashkenazim…..but am Ashkenazi …Ì am still waiting, after asking many precise questions…for a proper logic detailed substantial genetical answer…But no one seems able to tell me what does really mean this Result….
Absurd affirmations without scientfical details and general assertiosn aren’t a proof of and I woulsd appreciate to UNDERSTAND something of these peremptory assertions.
I know I am an ZAshkenaze since I am able to think about it and don’t need genetics to know that!But i wouls appreciate to have a course and details to explain How these results have a sense?? I don’t enter in any eerie of characteristics and am a mix of North and South european celtic germanic slavic and some Siberian and some trace from Neandertal & african immune system…OK…. But then, What is the Ashkenaz profile of that genomic distribution?For Godsake!
Hello JAK2,
I don’t totally understand what you are asking but 23andMe can determine if someone has Ashkenazi ancestry within the last couple of generations. I hope this helps.
Hello. I found your page while searching for Ashkenazi DNA Ireland.
On the sixth and ninth chromosomes I have markers for Ashkenazi. All of my ancestors are from Ireland. Both Protestant and Catholic, both northern and Republic of Ireland.
Is there a simple explanation as to population that would have contributed this miniscule but interesting genetic ancestry?