[Genetics] Y-Dna Haplogroups distribution in Sardinians

Introduction

In human genetics, an Y-chromosome DNA haplogroup'  is a haplogroup defined by differences in the non genetic recombining portions of DNA from the Y chromosome (called Y-DNA).

Y-DNA Haplogroups define the most recent patrilineal (male-lineage) ancestors of all living humans and so they can establish from where a single individual or an entire population come from.

Y─ DNA Adam

Haplogroup A0 Haplogroup A1 BT Haplogroup B CT DE Haplogroup D Haplogroup E CF Haplogroup C Haplogroup F Haplogroups F1-F4 Haplogroup G Haplogroup H IJK Haplogroup IJ Haplogroup I Haplogroup J Haplogroup K K* LT Haplogroup L Haplogroup T MNOPS Haplogroups K1-K4 Haplogroup M Haplogroup NO Haplogroup N Haplogroup O Haplogroup P Haplogroup Q Haplogroup R Haplogroup S

Estimation of the distribution of Y-Dna Haplogroups in Sardinian People:

	I	R1b	G2a	J2	J1	E1b1b	T + (L)	Q
Sardinia	45/37%	25/22%	15/11%	10%	2.5/2%	10/5%	1.5/0%	2%

Y-dna haplogroups distribution in Europe

Haplogroup I Y-DNA

Between 37-45% of Sardinians belong to the I Y-dna Haplogroup, it is today spread almost exclusevely in Europe and it is found in 1/5 of the European Population.

The time of origin of this haplogroup is estimated between 25,000 - 30,000 years BP, placing the Haplogroup I founding event approximately contemporaneous with the Last Glacial Maximum (period in the Earth's climate history when ice sheets were at their maximum extension). It is the most ancient Y-dna haplogroup present in Europe today.

Out Sardinia the Haplogroup I shows high prevalence only in Scandinavia, Northern Germany and the Balkans, in particular in Croatia, Bosnia and Herzegovina, Montenegro and Serbia.

Haplogroup I

Haplogroup I has two major subclades, one called I1 that has the highest frequency in the Northern Europe (mainly in Scandinavia) and another one called I2a prevailing in South Europe, in particular in the west balkanic region and in Sardinia.

Subclade I2a

Furthermore, the haplogroup I of the indigenous  Sardinians is the I2a1 subtype, formerly known as I-M26, which is almost unique to the island, though it  has also distribution in other areas of Western Europe, mainly in Iberia, in Particular among the Basques and among people living on the Pyrenees Range, mainly in the Department of Béarn In France. It is found in lower percentages also in Brittany, England, Sweden and Corsica. 
The highest frequency of this subclade is found among Sardinians from the most inaccessible and remotest mountainous regions of Barbagia and Ogliastra, in the Central and East part of the island.

Subclade I2a1 (shown as M26 in the map)

Haplogroup R1b Y-DNA

The Haplogroup R1b is the most frequently occurring Y-Dna haplogroup in Western Europe, and the second most frequent in Sardinians. Its frequency is between 22-25%, it is more spread among Northern Sardinians, in particular in Gallura (North East Sardinia). 

Haplogroup R1b

Main subclade of the Haplogroup R1b found in Sardinia is the R1b1a2 (R-M269) also known as S116, whose highest frequency is found  in Scotland (71%), Spain (70%) and in France (60%).

Haplogroup G2a Y-DNA

Haplogroup G is the 3rd most common Y-DNA haplogroup in Sardinian People, with a distribution estimated between 11% and 15%, mainly in the north part of the island and on the highlands of central regions. It spread on the island with the diffusion of the neolithic farmers from Asia.

It has an overall low frequency in most populations but is widely distributed within many ethnic groups of the Old World in Europe (especially in alpine regions) and West Asia (Caucasus), too. Highest percentage of this Haplogroup is found among the Georgians.

In Europe west of the Black Sea Haplogroup G is found at about 5% of the population on average throughout most of the continent. 

In western Austria, in the Tyrol  the G percentage can reach 8% or more, recently the detection of the genome of Ötzi the Iceman, the well-preserved natural mummy of a man who lived about 3,300 BCE, discovered on the Alps in 1991, revealed that he belonged to a rare subclade of the Haplogroup G, called G2a4 present today almost exclusively in Corsica and Sardinia.

Haplogroup J2a Y-DNA

The J2a haplogroup shows a frequency of 9.9% or lower in Sardinians. It probably was originated in the Caucasus region, among 15,000 and 20,000 years ago. Highest frequencies of it are today present among Northern Caucasians such as the Ingush and the Cechens. In Europe it is mainly spread in South East Europe and in Central and South Italy. It appeared in Europe in the Neolithic.

Haplogroup E1b1b Y-DNA

The E1b1b haplogroup shows low frequency in Sardinia between 5% and  10%. Haplogroup E1b1b (formerly E3b) represents the last direct major migration from Africa into Europe. It is believed to have first appeared in the Horn of Africa . In Europe it has the highest distribution in the South East. In mainland Italy it shows frequencies of 11% in the North, 10% in Central Italy, 18,5% in South and 17% in Sicily.

Haplogroup Q Y-DNA

The Haplogroup Q is rare in Sardinia (2%), in Europe it shows the highest frequencies among Norwegians, Swedish, Slovaks and Ukrainians. The place of origin of it is Siberia and Central Asia, and today it shows the highest diffusion among the Native Americans. 

Haplogroup R1a Y-DNA

In Europe R1a is found at highest levels in the North East among peoples of Eastern European descent Sorbs, Poles, Russians and Ukrainians from 50 to 65%. In Sardinia it is rare, but there are pockets of unusual concentrations in some isolated areas of the inland, like in the village of Sorgono (the most central and further sardinian town from the sea coasts) where 5% of population belongs to this haplogroup.