The Italian genome reflects the history of Europe and the Mediterranean basin

[PNGarrison]

European Journal of Human Genetics (2016) 24, 1056–1062; doi:10.1038/ejhg.2015.233; published online 11 November 2015

http://www.nature.com/ejhg/journal/v24/n7/full/ejhg2015233a.html

open access

The Italian genome reflects the history of Europe and the Mediterranean basin

Giovanni Fiorito1,2, Cornelia Di Gaetano1,2, Simonetta Guarrera1,2, Fabio Rosa2, Marcus W Feldman3, Alberto Piazza1,2 and Giuseppe Matullo1,2

1Department of Medical Sciences, University of Turin, Turin, Italy
2HuGeF Human Genetics Foundation, Turin, Italy
3Department of Biology, Stanford University, Stanford, CA, USA
Correspondence: Professor G Matullo, Department of Medical Sciences, University of Turin, Via Nizza 52, Turin 10026, Italy. Tel: +39 011 6709542; E-mail: [email protected]

Received 27 January 2015; Revised 22 September 2015; Accepted 30 September 2015
Advance online publication 11 November 2015

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Abstract
Recent scientific literature has highlighted the relevance of population genetic studies both for disease association mapping in admixed populations and for understanding the history of human migrations. Deeper insight into the history of the Italian population is critical for understanding the peopling of Europe. Because of its crucial position at the centre of the Mediterranean basin, the Italian peninsula has experienced a complex history of colonization and migration whose genetic signatures are still present in contemporary Italians. In this study, we investigated genomic variation in the Italian population using 2.5 million single-nucleotide polymorphisms in a sample of more than 300 unrelated Italian subjects with well-defined geographical origins. We combined several analytical approaches to interpret genome-wide data on 1272 individuals from European, Middle Eastern, and North African populations. We detected three major ancestral components contributing different proportions across the Italian peninsula, and signatures of continuous gene flow within Italy, which have produced remarkable genetic variability among contemporary Italians. In addition, we have extracted novel details about the Italian population’s ancestry, identifying the genetic signatures of major historical events in Europe and the Mediterranean basin from the Neolithic (e.g., peopling of Sardinia) to recent times (e.g., ‘barbarian invasion’ of Northern and Central Italy). These results are valuable for further genetic, epidemiological and forensic studies in Italy and in Europe.

[John McCoy]

Does anyone else see the implications for the problem of measuring ethnic origins? How can "Italian" origins be accurately detected in the face of "remarkable genetic variability among contemporary Italians"?

[CTCoons]

Considering 1/2 the DNA get 'discarded' every generation, it's amazing what we can discover.

Think of the stories; of those people who came to that region and left hints behind in the genes of their descendents.

[MMaddi]

Does anyone else see the implications for the problem of measuring ethnic origins? How can "Italian" origins be accurately detected in the face of "remarkable genetic variability among contemporary Italians"?

I take the quote you've cited to mean that, while there is distinguishable variation among Italians from different parts of the country, there still is the ability to distinguish overall that someone is Italian of some sort versus some sort of northern European. I think that Italians do have clear signals of DNA from the Greece/the Balkans and the Middle East/North Africa.

Right now myOrigins lumps everyone in Mediterranean Europe as "Southern European" - Spain/Portugal, Italy and Greece/the Balkans. But 23andMe does split those three off as separate categories. However, most people with full Italian ancestry at 23andMe do get some Balkans and Middle East/North Africa and sometimes Iberian. At FTDNA, my Origins will usually give someone with full Sicilian/southern Italian ancestry 50-60% Southern European and 40-50% Middle Eastern, with in some cases 5-10% Jewish Diaspora.

[Anthony]

I take the quote you've cited to mean that, while there is distinguishable variation among Italians from different parts of the country, there still is the ability to distinguish overall that someone is Italian of some sort versus some sort of northern European. I think that Italians do have clear signals of DNA from the Greece/the Balkans and the Middle East/North Africa.

Right now myOrigins lumps everyone in Mediterranean Europe as "Southern European" - Spain/Portugal, Italy and Greece/the Balkans. But 23andMe does split those three off as separate categories. However, most people with full Italian ancestry at 23andMe do get some Balkans and Middle East/North Africa and sometimes Iberian. At FTDNA, my Origins will usually give someone with full Sicilian/southern Italian ancestry 50-60% Southern European and 40-50% Middle Eastern, with in some cases 5-10% Jewish Diaspora.

Mike, i think the Roman Empire and later Byzantine Empire had a huge role to play in Southern Italian/Sicilian admixture, probably more migrations than most people would assume/know of, curious to know how much Middle Eastern do Central and Northern Italians get?

[MMaddi]

Mike, i think the Roman Empire and later Byzantine Empire had a huge role to play in Southern Italian/Sicilian admixture, probably more migrations than most people would assume/know of, curious to know how much Middle Eastern do Central and Northern Italians get?

I don't have enough experience with the myOrigins results of people with Central or Northern Italian ancestry versus Southern Italian ancestry to comment directly. However, here's a quote from the paper (see link in first post) that's the subject of this thread. It may provide a partial answer to your question. I recommend reading the entire paper, only 7 pages, and taking a look at the supplementary material.

"Admixture events introducing Northern-Central European ancestry into Italy were estimated to have occurred during the so-called ‘Migration Period’ after the Roman Empire collapsed (476 CE), with the consequent decline in population. After that the ‘Barbarian invasions’ took place, with migratory waves from Northern-Central Europe to Northern-Central Italy. It may be speculated that the estimated Northern-Central European ancestry in contemporary Italians is also the effect of subsequent Italian population growth, as previously reported by studies on mitochondrial and Y-chromosome DNA from a genetic isolate in Northern Italy, suggesting that Germanics (Lombards in particular) settled in Northern Italy during the ‘Migration Period’ and may have contributed to the foundation of some communities in Northern Italy. Finally, admixture events involving the Southern Italian population were inferred to have occurred about 1000 y.a., coinciding with The Norman conquest of Southern Italy that spanned most of the eleventh and twelfth centuries and involved many battles and independent conquerors. A much more detailed analysis of geographically well-distributed samples from Southern Italy is required to validate our findings, while a large genetic contribution to the island of Sicily from Greece has previously been estimated."

[Anthony]

I don't have enough experience with the myOrigins results of people with Central or Northern Italian ancestry versus Southern Italian ancestry to comment directly. However, here's a quote from the paper (see link in first post) that's the subject of this thread. It may provide a partial answer to your question. I recommend reading the entire paper, only 7 pages, and taking a look at the supplementary material.

"Admixture events introducing Northern-Central European ancestry into Italy were estimated to have occurred during the so-called ‘Migration Period’ after the Roman Empire collapsed (476 CE), with the consequent decline in population. After that the ‘Barbarian invasions’ took place, with migratory waves from Northern-Central Europe to Northern-Central Italy. It may be speculated that the estimated Northern-Central European ancestry in contemporary Italians is also the effect of subsequent Italian population growth, as previously reported by studies on mitochondrial and Y-chromosome DNA from a genetic isolate in Northern Italy, suggesting that Germanics (Lombards in particular) settled in Northern Italy during the ‘Migration Period’ and may have contributed to the foundation of some communities in Northern Italy. Finally, admixture events involving the Southern Italian population were inferred to have occurred about 1000 y.a., coinciding with The Norman conquest of Southern Italy that spanned most of the eleventh and twelfth centuries and involved many battles and independent conquerors. A much more detailed analysis of geographically well-distributed samples from Southern Italy is required to validate our findings, while a large genetic contribution to the island of Sicily from Greece has previously been estimated."

With Northern Italians this information is expected, the only thing that puzzles me is for Southern Italians, how much possible migrations could have taken place after the Norman Conquest? I would have expected it to be earlier.

[MMaddi]

With Northern Italians this information is expected, the only thing that puzzles me is for Southern Italians, how much possible migrations could have taken place after the Norman Conquest? I would have expected it to be earlier.

I too thought that didn't sound right. The authors seem to concede that point when they write, "A much more detailed analysis of geographically well-distributed samples from Southern Italy is required to validate our findings, while a large genetic contribution to the island of Sicily from Greece has previously been estimated."

From my reading of Sicilian medieval history, I don't think there were that many Normans involved in taking the island away from Muslim rule. The Norman rule for most of the 12th century was only at the national level through the royal court in Palermo. The local government was left in the hands of the Greek and Arabic speaking leaders who had been conquered. Even some important officials at the royal court were Greek or Arabic speakers, not Normans. It doesn't seem to me that the Norman takeover had much of a demographic effect on the Sicilian population and probably not the southern Italian population either.

[Anthony]

I too thought that didn't sound right. The authors seem to concede that point when they write, "A much more detailed analysis of geographically well-distributed samples from Southern Italy is required to validate our findings, while a large genetic contribution to the island of Sicily from Greece has previously been estimated."

From my reading of Sicilian medieval history, I don't think there were that many Normans involved in taking the island away from Muslim rule. The Norman rule for most of the 12th century was only at the national level through the royal court in Palermo. The local government was left in the hands of the Greek and Arabic speaking leaders who had been conquered. Even some important officials at the royal court were Greek or Arabic speakers, not Normans. It doesn't seem to me that the Norman takeover had much of a demographic effect on the Sicilian population and probably not the southern Italian population either.

Yes you summed it up perfectly, from what I have read the data seems consistent as well in terms of Medieval Sicily, there was migrations of Northern Italians (from the regions of Piedemonte and Liguria) to the Enna region as it was heavy depopulated after the fallout of Norman conquest, there also seems to be a bit of migrations from these same regions to Catania and Messina regions during the Ghibellines and Guelph wars. There was known Muslims living in Sicily up until the early 13th century, but there was a deportation to Lucera (Foggia), any Arabs/Berbers left would have converted and probably spread throughout the Island.

[Ariana]

My DNA results

Mike, i think the Roman Empire and later Byzantine Empire had a huge role to play in Southern Italian/Sicilian admixture, probably more migrations than most people would assume/know of, curious to know how much Middle Eastern do Central and Northern Italians get?

Anthony,
I have northern Italian ancestry on both sides of the family and my DNA results were:

48% Italy/Greece
25% Western Europe
18% Scandinavia
6% British
3% Eastern European

I came out as 100% European.

While it might vary, I don't think that many native northern Italians have a lot of Middle Eastern in them. We tend to be a mix of northern and southern Europe.

[AFH]

Anthony,
I have northern Italian ancestry on both sides of the family and my DNA results were:

48% Italy/Greece
25% Western Europe
18% Scandinavia
6% British
3% Eastern European

I came out as 100% European.

While it might vary, I don't think that many native northern Italians have a lot of Middle Eastern in them. We tend to be a mix of northern and southern Europe.

What area of northern Italy is your ancestry from?

[Anthony]

Anthony,
I have northern Italian ancestry on both sides of the family and my DNA results were:

48% Italy/Greece
25% Western Europe
18% Scandinavia
6% British
3% Eastern European

I came out as 100% European.

While it might vary, I don't think that many native northern Italians have a lot of Middle Eastern in them. We tend to be a mix of northern and southern Europe.

Ariana,

For the Italy/Greece you mean Southern European right? Yes I agree with you it varies, Northern Italians might get some Asia Minor, this is most probable of Near Eastern farmers, but for some reason I have the suspicion that Italians from Piemonte, Valle D'Asota and Lombardia would either get very little or none, is your ancestry from there? I wonder where your 6% British came from? That should be interesting to pursue.

[MoberlyDrake]

My grandfather was born in Cappelle sul Tavo, a village not far from Pescara in the Abruzzo region. I found this information on Cappelle online:

"The name probably derives from a number of small "cappelle", chapels, among the woods. The name "Cappelle" also appears in documents of the XI and XII centuries and is represented in the emblem of the town, showing 2 Gothic chapels. The first information about the medieval village date back to the XII century. The area was a busy route for pilgrims and travellers, and in the XVI century there was a military headquarter. In the XVII century farmers from Jugoslavia were brought to work on the lands of the Barons of Civita Sant'Angelo. In the XVIII century it belonged to the Figliola family, then it came under the jurisdiction of the commune of Montesilvano. In 1833 the King of Naples gave it to his swiss Baron Rodolfo de Landerset, who had married a local lady. "

Although I don't get many myself, my father and both of my cousins who tested here have a number of Croatian matches. My sister, who tested at Ancestry is also getting Croatian matches, plus some from Malta and some from Russia.

[Ariana]

What area of northern Italy is your ancestry from?

Hi,
My parents are both from the little alpine town of Asiago, in Italy's Veneto region.

[Ariana]

Ariana,

For the Italy/Greece you mean Southern European right? Yes I agree with you it varies, Northern Italians might get some Asia Minor, this is most probable of Near Eastern farmers, but for some reason I have the suspicion that Italians from Piemonte, Valle D'Asota and Lombardia would either get very little or none, is your ancestry from there? I wonder where your 6% British came from? That should be interesting to pursue.

Hi Anthony,
My parents are from a small alpine town, Asiago, in Italy's north east.
I too was intrigued by the 6% British, so I followed your advice and did some research. I found this very interesting article:

http://news.bbc.co.uk/2/hi/programmes/from_our_own_correspondent/9522135.stm

It talks about how British soldiers fought alongside Italians during WWI, and ended up in... Asiago!!