Genetic studies on Bulgarians

The Bulgarians are part of the Slavic ethnolinguistic group. However, the Bulgarians and most other South Slavs are characterized by a prevailing genetic substrate that is different than that of the North Slavs. The two groups are separated, sharing only a modest gene flow. This phenomena of two genetically distinct groups of Slavic peoples is explained by the assimilation of previous indigenous populations by the medieval Slavic settlers in the Balkans.

Y DNA

File:Haplogroups europe.png

Prevailing hgs among Euroepans

Bulgarians show the highest diversity of haplogroups in Europe, marked by significant (> 10%) frequencies of 5 major haplogroups (compared to Atlantic Europe, dominated by > 50% R1b). Most Bulgarians belong to three unrelated haplogroups, 20% of whom to I-M423 (I2a1b), 18% to E-V13 (E1b1b1a1b1a) and 17.5% to R-M17 (R1a1a), but the biggest part belongs to macro-haplgoroup R (~28%). The major haplogroups, groupped by age of around 20 kya, are:

File:I2 Haplogroup.gif

Hg I-P37 (I2a1, aka. I2a) distribution mainly based on the map of Rootsi (2004) confirming that no Bulgarian samples data was considered for the map making.

• Haplogroup I-L460 (I2a) is presented at levels ~22% according to 808 Bulgarian male samples of the largest-scale study from 2013. By higher levels are defined the profiles of Romanians, Ukrainians and all South Slavs other than Bulgarians. Evidence points to European origin for macro-haplogroup I, and Levantine for its immediate ancestor- IJ. Its exclusive and now patchy distribution within Europe suggested a very early entry in to Europe during Palaeolithic colonization, which was confirmed by the lack of its ancient DNA outside of the continent and ~13,000 years old European Cro-Magnon remains belonging to I2a. Bulgarian Hg I2a most often belongs specifically to the P37.2, M423 branch ("Hg I2a1b"), representing 20% of Bulgarian males. According to some data, Bulgarian males who belong to M423, belong to CTS10228 Dinaric (I2a1b2a1), the prevalent clade in eastern Europe, and none of them belongs to the Disles L161 branch or the CTS595 branch found in west Europe and Sardinia. The Dinaric is descended by several 'only child' sublclades and it is suggested that its most recent common ancestor is aged only 2200 years making it the youngest and most common micro-group. It makes up an absolute majority among the highest populations. The largest marker group among Bulgarians is Dinaric-North, the largest SNP group is Z17855, being the prevailing clade in the eastern Balkans and rare elsewhere. Second major part are representatives of Dinaric-South S17250+, which is the most common subclade among west Balkan peoples, the clades Dinaric-North S17250+ and Y4460+ that are traditional for the North Slavic peoples are also represented at lower levels. These SNP groups separated before the Slavic expansion in the Balkans. Thus, the highest frequncy of I2a that is observed in the Balkans today was present before the expansion and is owed to indigeneous tribes, in particular Thracians for Romania and the region. Initially a Holocene expansion of I2a in Southeastern Europe is supposed; however the homogeneity of Balkan Hg I2 and its star-like clustering suggests a far more recent expansion time. Around 2% of Bulgarian males belong to the subclade M223 (I2a2a) found mostly around Germany. I2a2 is the most frequent haplogroup of European male remains dated to the Metal Ages, while I2a1 and I2a1b are most common on Mesolithic remains, as such they were the primary haplogroups of pre-historic European hunter-gatherers.

Distribution of E-M78 according to Semino (2004) (no data on Bulgarians used, probable frequency)

• Haplogroup E-V68 (E1b1b1a) is presented at levels ~19.5%. The ultimate origin of E-V68 points to northeastern Africa, specifically near the Nile and Lake Alexandria. Thus this haplogroup represents a more recent Bronze Age "out of Africa" movement into Europe via the Balkans. The macro-haplogroup E still prevails in most of the African continent, but through the long-term migrations the sub-Saharian maternal lineage Hg L was lost lacking completely in the Balkans. Holocene movement into the Near East is proposed, then several thousand years ago, a movement into the Balkans. All V68-positive Bulgarians belong to its M78 subclade, which is the prevailing haplogroup in most of northeast Africa and around the Balkans. The presently mostly European V13 (E1b1b1a1b1a) originated in western Asia according to the most plausible scenario and is presented at ~18% among Bulgarian males. According to deeply traced data its internal structure is divided among Z5016, Z5017 and S7461. Recent findings of V13 in a Neolithic context in Iberia (dated to ~ 7 kya) give a terminus ante quem. However, it might have really begun to expand in the Balkans somewhat later, perhaps during the population growth of the Bronze Age. Like I-P37 above, it is spread throughout Europe but peaks in the Balkans, only for the Albanians, Greeks, Macedonians, Macedonian Romani, Montenegrins and Serbs are recorded higher levels than Bulgarians.

File:R1a1a distribution.png

Hg R-M420 (R1a) distribution per Underhill 2009, which confirmes that no data of Bulgarian samples was considered in the map making

• Haplogroup R-M420 (R1a) is identified at 17.5%. It is the dominant group among most Slavs, Hungarians and the Indostan area. The M458 branch, which is the most common clade in Poland, the Czech Republic and Croatia, is present in Bulgarians at 7.5%. The percentage of Z93 had not been revealed by the study and some of its Bulgarian authors attempted to propagandize that the DNA results consider the Bulgarians mainly descendants of Indo-European Bulgars coming from Asia in the Middle Ages. Later, other studies revealed that the R1a subclades that are limited to Europe and separated from their Asian relative ~5000 years ago, make up 97% of Bulgarian R1a, divided by the largest clades the Bulgarian R1a structure would be nearest to the Estonian and Czech by composition. After over 60 Bulgarian R1a carriers had been studied, it was revealed that M458 and Z280 both constitute 45% of their subclades, 7% constitute their parent Z282 and only 3% is constituted by the Asian branch Z93, that is the most common subclade from China to Anatolia, no west European subclade was detected. As such, the R1a frequency among Bulgarians may only be the result of descendants of east European satem peoples such as early Slavs, Thracians and Illyrians. R1a with a prevailing M458 component makes up the majority in the former Haskovo province. Z280 is consistently outnumbered by M458 throughout whole eastern and central Bulgaria, which might be the result of recent Slavic expansions. M458 is the dominant R1a clade in the regions roughly corresponding to eastern Bulgarian dialects which share many similarities with the Polish language as opposed to the western dialects which tend to be more related to Slovak and Ukrainian. Deepely tracing data reveals that the most common Bulgarian micro-clade appears to be the L1029 subclade (R1a1a1b1a1b1) of M458, which prevails in most of the eastern Balkans and various spased parts of central and northern Europe, and is 2-3,000 years old. Sufficient data on younger clades has so far been unavailable.
• Haplogroup R-M343 (R1b): present in Bulgarians at ~11%. R1b is the most frequently occurring haplogroup around Ural and Chad, in most of western Europe and the adjacent islands. The Bulgarian internal structure is heterogeneous and 4% of Bulgarian males carry western European subclades. At least 2% are carriers of the 'Italo-Celtic' branch U152, another 1 percent belongs to the U106 branch that corresponds with the spread of Germanic peoples. The ancestral L23 and Z2103 branch show a clear relationship with Anatolia and the Near East. The branch turned to be the dominant clade of the Yamna culture in far eastern Europe and in addition to the Middle East it is still the dominant clade of R1b there and in most of Central Europe. Most Bulgarians (6%) belong to the branch, the majority of them belong to its subclade Z2110 (R1b1a1a2a2c1a), which today is likely limited only around Europe. The overall evidence suggests that the macro-haplogroup R arose in southern or central Asia descending from Haplogroup IJK. The subsequent path into Europe, and the major settlement is thought to have happedned in the Bronze Age by the Kurgan hypothesis, R1 clades are found at minority levels in Europe since the Mesolithic; a subsequent Balkan entry of R1b into Europe is a major theory.
• Haplogroup J-M172 (J2) is presented at levels 10.5%. Higher levels of it are observed in the Balkans as far as Bosniaks, Italians, while Anatolia and the surroundings are dominated by the group. Whilst its origin is north Levantine, its current pattern reflects more recent events connecting the Aegean and western Anatolia during the Copper and Bronze Ages, as well as Greek and Phoenician colonization around the Mediterranean. Several subclades within J2 are present: J-M410 (J2a) is represented at 6% and J-M12 (J2b) at 4%, the prevailing is the L26 deep subclade of J2a, it is furtherly divided into M67, M92, L24 and other clades.

Finally, there are also some other Y-DNA Haplogroups presented at a lower levels among Bulgarians ~ 20% all together, as G-P15 (G2a) at ~5%, I-M253 (I1)at ~4% of which mostly mostly Scandinavian L22, Yutlandian Z58 and continental Z63, J-M267 (J1) at ~3.5%, E-M34 (E1b1b1b2a1) at ~2%, T-M70 (T1a) at ~1.5%, at less than 1% Haplogroup C-M217 (C2), H-M82 (H1a1), N-M231 (N), Q-M242 (Q), L-M61 (L), I-M170 (I), E-M96 (E) excl. M35, R-M124 (R2a), E-M81 (E1b1b1b1a), E-M35 (E1b1b1).

According to an older study of 127 Bulgarian males, 30% of them belong to haplogroup R (17% R1a, 11% R1b, 2% R*); 27.5% to haplogroup I; 20% to E; 18% to J, 1.5% to G; 1.5% to H; and 1% to T.

According to another study involving 126 Bulgarian males, frquencies are the following, haplogroup I 30% (25.5% I2a, 4% I1); E 20,5%; R 17.5%(R1b 11%, R1a 6%); J 17.5% (16% J2); G 5.5%, Q 4%, L 1%, T 1%, unknown 3%.

According to another study involving 100 Bulgarian males, 34 of them belong to haplogroup I (29 to I2a, 3 to I1); 30 to R (16 to R1a, 14 to R1b); 21 to haplogroup E (20 to E1b1b1a); 9 to J, 2 to G, 2 to T and 1 to N.

The overall profile of 808 Bulgarian samples, according to the highest level of phylogenetic analysis calculating distribution of hgs R1a1a7, R1а1, R1b1a2, R2a, I, E1b1, E1b1b1, E1b1b1a, E1b1b1b, J2b, J2a, J2a1b, J1, G, T, NO, C, H, Q, L, A and B, is positioned nearest to the Romanians per 147 their samples, also backed by studies as early as 2000, however the analysis of the Bulgarian study showed inaccuracy in some aspects, the data for almost all European populations was based on less than 100 samples per population which led massively to genetic drift of many population datasets according to alternative more extensive studies on these populations. Furthermore the analysis did not even involve the populations Macedonians, Serbians, Montenegrins and Slovaks. The study of the 149 Romanians by whose data they came out most proximal to Bulgarians concludes that Romanians are closer to Ukrainians and Hungarians than to the Bulgarian group sampled by the study. Bulgarians are situated nearer to populations such as Berbers and Sudanese than to Turks and Poles, which proximity also applies for nearby populations to Bulgarians that were under Ottoman Turkish rule for centuries. This situation would not be the same if the analysis calculates distance by considering more recent subclades, e.g. EV13 instead of EM78, similarily Y-DNA analyses of distribution of haplogroups of pre-Holocene age determine Norwegians and Sardinians more proximal to Bulgarians than Poles and Russians. Some Central Europeans are situated very distant per data of the phylogenetic Bulgarian study because of scarce datasets containing remarkable genetic drift. For most compared European peoples datasets were taken from Battaglia (2008) which does not involve more than 100 samples per population. Many large scale studies refuted the frequencies from the scarce datasets of Battaglia as inaccurate determining that the observed frequency of R1a of Battaglia among Hungarians (57%) was the result of exceptionally strong genetic drift due to only 53 samples taken and this extended a lot their genetic distance against Bulgarians who actually by the most extensive data so far are actually the most proximal Europeans to the Hungarians. The largest-scale study of the Hungarians (n=219) determined that their R1a frequency is only 26% and that levels of I2 are higher than the data of Battaglia. It determined that the remaining Finno-Urgic peoples are genetically their furthest populations, and clearly confirmed that the closest Europeans to the Hungarians are the Bulgarians, however the same study determines the Yugoslavs as the nearest population to Bulgarians. Similarly, some reckon that the contribution of Bulgars to the modern Bulgarian genetic pool is hardly recognisable. It is unclear why the extensive datasets and the most proximal Slavic populations to the Bulgarians were excluded from the phylogenetic analysis of the Bulgarian study selectively. According to the study Bulgarians are related to the population of Greek Macedonia where hg I2 is prevalent per Battaglia. Some frequencies in the northern Greek regions of Serres, Thessaloniki, Nea Nikomedeia and Western Thrace show common differientation from peninsular and insular Greeks at the expense of more similaraties to Slavs by prevalent hgs R1a or I, anyway other studies determine prevalent hg E-V13 in the region and lower frequency of hg I in northern than in southern Greece.

Other Y-DNA studies considered the Bulgarians closest either to Macedonians, Serbs, Bulgarian Turks or Gagauzes, followed either by some of these or by Romanians, or Bosniaks.According to DNA data for 17 Y-chromosomal STR loci in Macedonians, the Macedonian population has the lowest genetic distance against the Bulgarian population (0.0815).

Regional distribution

The Bulgarian population as one of the most heterogeneous populations is furthermore heterogeneous regionally, or rather heterogeneous on frequencies. All of the 5 major haplogroups may be most common in different regions which may be due to the few people sampled in many regions. No participants admitting for being minorities are recorded except Muslim ethnic Bulgarians in the results below. Due to the size of samples taken some regions perhaps represent genetic drift which is more likely to happen in heterogeneous regions.

Distribution of haplgoroups in Sofia City Province per 59 samples:

• R: 34%
  • R-M420: 20%
  • R-M343: 14%
• I: 32%
  • I-L160: 27%
  • I-M253: 3%
• J: 15%
  • J-M172: 8%
  • J-M267: 7%
• E: 10%
  • E-V13: 9%
• G-P15: 3%
• H-M82: 3%
• T-M70: 2%

Distribution of haplogroups in the former Plovdiv Province per 159 samples:

• I: 30%
  • I-L160: 23%
  • I-M253: 6%
• R: 28%
  • R-M420: 16%
  • R-M343: 12%
• E: 24%
  • E-V13: 20%
• J: 11%
  • J-M172: 9%
  • J-M267: 2%
• G-P15: 4%
• T-M70: 1%
• H-M82: 1%
• N: 1%
• Q: 1%

Distribution of haplogroups in the former Sofia Province per 257 samples:

• I: 30%
  • I-L160: 25%
  • I-M253: 4%
• R: 27%
  • R-M420: 18%
  • R-M343: 9%
  • R2: <1%
• E: 19%
  • E-V13: 14%
• J: 15%
  • J-M172: 11%
  • J-M267: 4%
• G-P15: 7%
• C-M217: <1%
• T-M70: <1%
• H-M82: <1%
• N: <1%
• Q: <1%

Distribution of haplogroups in the former Varna Province per 15 samples:

• I: 40%
  • I-L460: 33%
  • I-M253: 7%
• R: 27%
  • R-M420: 13%
  • R-M343: 13%
• E: 26%
  • E-V13: 20%
• J: 7%
  • J-M172: 7%

Distribution of haplogroups in the former Lovech Province per 62 samples:

• E: 26%
  • E-V13: 24%
• R: 24%
  • R-M420: 20%
• J: 21%
  • J-M172: 18%
  • J-M267: 3%
• I: 19%
  • I-L620: 16%
  • I-M253: 3%
• G-P15: 5%
• L, Q, T-M70: per 2%

Distribution of haplogroups in the former Burgas Province per 45 samples:

• R: 29%
  • R-M343: 18%
  • R-M420: 11%
• E: 27%
  • E-V13: 18%
• J: 24%
  • J-M172: 18%
  • J-M267: 6%
• I: 16%
  • I-L620: 16%
• G-P15: 4%

A PCA analysis determined that the population of Haskovo Province is at shorter genetic distance to the population of the Czech Republic than to any other Bulgarian province, and that only the population of Burgas Province is closer to Haskovo than the Hungarian population, furthermore only comparison with two more Balkan or Slavic foreign populations(Greece and Croatia) is available and all other Slavic populations are excluded from this analysis. Distribution of haplogroups in the former Haskovo Province per 41 samples:

• R: 44%
  • R-M343: 29%
  • R-M420: 15%
• E: 32%
  • E-V13: 29%
• J: 12%
  • J-M172: 10%
  • J-M267: 2%
• I: 10%
  • I-L260: 7%
  • I-M253: 2%
• T-M70: 2%

Distribution of haplogroups in the former Razgrad Province per 21 samples:

• E: 38%
  • E-V13: 38%
• R: 24%
  • R-M343: 14%
  • R-M420: 10%
• G-P15: 14%
• J: 10%
  • J-M172: 10%
• I: 9%
  • I-L620: 9%
• T-M70: 5%

Distribution of haplogroups in the former Montana Province per 80 samples:

• R: 29%
  • R-M420: 23%
  • R-M343: 6%
• E: 26%
  • E-V13: 20%
• I: 25%
  • I-L620: 19%
  • I-M253: 6%
• J: 13%
  • J-M172: 8%
  • J-M267: 5%
• G-P15: 4%
• C-M217: 1%
• Q: 1%
• T-M70: 1%

mtDNA

Prevailing mtDNA hgs

Complimentary evidence exists from mtDNA data. Bulgaria shows a very similar profile to other European countries – dominated by mitochondrial haplogroups Hg H (~42%), Hg U (~18%), Hg J/Hg T (~18%), and Hg K (~6%). Like most Europeans, H1 is the prevailing subclade among Bulgarians. Most of the U-carriers belong to U5 and U4. The subclades of Haplogroup H may have not been studied but subclusters H1b and H2a are more common in Eastern than in Western Europeans. Recent studies show greater diversity within mt Haplogroups than once thought, as sub-haplogroups are being discovered, and often separate migrations and distributions of the Y-DNA haplogroups. While the Y-DNA variation in Europe is clinal, the mitochondrial is not.

The results of the mitochondarial analyses find the Bulgarians more related to North Slavs. The general mtDNA analyses of the study find the Bulgarians in a cluster with Central Europeans, but others find them more related to Balkan peoples, or to both at the same time. According to the largest-scale mtDNA Bulgarian study involving 996 Bulgarian samples, comparing distribution of hgs H, H5, HV, HV0, R0a, J, U1, U2, U2e, U3, U4, U5a, U5b, U6, U7, U8, K, N1, N2, X, M, Т1, Т2, the Bulgarians came out nearest to the Poles, followed by Ukrainians, Croats, Czechs, while neighbouring Turks, Romanians and Greeks remained more or very distant. Several other pan-European analyses of the same Bulgarian samples indicate that the neighbouring populations except the Macedonians are distant from the Bulgarians. According to these the Bulgarians are at minimal distance by mtDNA either to Hungarians, Szekelys, Slovaks or to Macedonians, followed either by Ukrainians, Croats or Czechs, while neighbouring populations such as Turks, Romanians, Serbs and Greeks remain more distanced. Italians also remain related according to these studies. Accotding to another analysis, Bulgarians despite being part of a Slavic mitochondrial cluster, are most related to Romanians, followed by Hungarians and Czechs, but distant to Balkan Albanians and Bosniaks, it was also found out that Bulgarians are very distant to all Asian and African populations, but are least distanced by mtDNA to the Arkhangelsk Oblast in Russia where also Y-DNA hg I2 prevails. A more recent pan-Slavic mtDNA plot analyzing genetic distance, situates Bulgarians as sharing their position with Czechs, Romanians, Macedonians and Hungarians, while other close groups to them are Slovaks, Estonians and Latvians. Others determined Albanians and Portuguese as most related to Bulgarians, others determined northern Europeans and Slavs, others Israeli however some of these analyses depend on minimal variance that changes the proximal distance. Other studies consider the Bulgarians closest to Romanians, followed by Italians and Iberians, while Poles, Slovaks, and Czechs are determined more distanced. This innovatively considered the Latin peoples at short genetic distance, which has never been confirmed with Y-DNA. It should noted none of the analyses on genetic distance compares the subclades of Haplogroup H except for H5 due to lacking data, however the structure of the haplogroup of some central European, Balkan and other peoples may be similar to the Bulgarian, at least by division of older subclades of haplogroup H.

MtDNA haplgroups of ~1000 Bulgarians:

• HV - 49%
  • H - 41%
    • H5 - 3%
  • HV - 4%
  • HV0 - 4%
• U - 18%
  • U1 - 1%
  • U2e - 1%
  • U3 - 2%
  • U4 - 4%
  • U5 - 8%
    • U5a - 5%
    • U5b - 3%
  • U6 - 0%
  • U7 - 1%
  • U8 - <1%
• JT - 18%
• K - 6%
• N - 5%
  • N1 - 3%
  • N2 - 2%
• X - 2%
• M - 1%
• L - <1%
• R0a - <1%
• Others - <1%

auDNA and overall

The European genetic structure (based on 273,464 SNPs). Three levels of structure as revealed by PC analysis are shown: A) inter- continental; B) intra-continental; and C) inside a single country (Estonia). D) European map illustrating the origin of sample and population size.

Network of 29 populations constructed with the Neighbor-net approach from FST distances based on the variation of autosomal SNPs.

Balto-Slavic comparison by A (atDNA), B (Y-DNA) and C (mtDNA plot).

Admixture analysis of autosomal SNPs of the Balkan region in a global context on the resolution level of 7 assumed ancestral populations: the African (brown), South/West European (light blue), Asian (yellow), Middle Eastern (green), North/East European (dark blue) and beige Caucasus component.

Whilst haploid markers such as mtDNA and Y-DNA can provide clues about past population history, they only represent a single genetic locus, compared to hundreds of thousands present in nuclear, autosomal chromosomes. However autosomal analyses often sample a small number of Bulgarians, however multiple autosomes tracing multiple ancestoral lines may be traced by an individual's 21 autosomes as opposed to one identical mtDNA or Y DNA sex chromosome whose inheritance is clinal. Analyses of autosomal DNA markers gives the best approximation of overall 'relatedness' between populations, presenting a less skewed genetic picture compared to Y DNA haplogroups. This atDNA data shows that there are no sharp discontinuities or clusters within the European population. Rather there exists a genetic gradient, running mostly in a southeast to northwest direction. A study compared all Slavic nations and combinined all lines of evidence, autosomal, maternal and paternal, including more than 6000 people for and at least 700 Bulgarians from previous studies, of which 13 were used for autosomal analysis. The overall data situates the southeastern group (Bulgarians and Macedonians) in a cluster with Romanians, and they are at similar proximity to Gagauzes, Montenegrins and Serbs who are not part of another cluster but are described as 'in between' clusters. Macedonians and Romanians consistingly keep being among most related to Bulgarians by au, mt, and Y-DNA a conclusion backed also by a pan-European autosomal study investigating 500,568 SNP (loci) of 1,387 Europeans sampling 2 Bulgarians, other more or less extensive data sets situate Bulgarians and Romanians as their nearest. Per HLA-DRB1 allele frequencies Bulgarians are also in a cluster with the same populations. The Balto-Slavic study itself calculated genetic distance by SNP data of the multiple autosomes and ranked most proximal to Bulgarians the Serbs, followed by Macedonians, Montenegrins, Romanians, Gagauzes, Macedonian Greeks apart from Thessaloniki, the rest of the South Slavs, Hungarians, Slovaks, Czechs, and then by Greeks from Thessaloniki, Central Greece and Peloponese. The East Slavs and Poles cluster together remaining less proximal to Bulgarians than Germans.

The study claims that the major part of the Balto-Slavic genetic variation can be primarily attributed to the assimilation of the pre-existing regional genetic components. For Slavic peoples correlations with linguistics came out much lower than high correlations with geography. The South Slavic group, despite sharing a common language, is separated and has largely different genetic past from their northern linguistic relatives genetically. Therefore, for the Bulgarians and most other South Slavs the most plausible explanation would be that their most sizable genetic components were inherited from indigenous Balkan pre-Slavic and pre-Bulgar population, which is also the similar case of most European peoples, whose genetic structure is dependent on geography rather than on language, dominant regional genes often predate the arrival of the current linguistic family by milleniums with some exceptions such as theEnglish people whose significant genetical impact was brought by the medieval Germanic settlers in the isles. Another pan-Slavic Y-DNA study concludes that most of the Southern Slavic group is distinct from their Northern Slavic relatives, whose homogeneity on the other hand stretches form the Alps to Volga end even as far as the Pacific Ocean in Russia. This means that there is a paternal genetic rather than a geographical factor separating these Slavic peoples. The South Slavs are characterized by featuring NRY hgs I2a and E plus 10% higher Mediterranean k2 autosomal component, while the Eastern and Western Slavs are characterized by the k3 component and hg R1a. The current differentiation of high I-P37 and lower R-Z282 among South Slavs and vice versa among North Slavs suggests it was present prior to the Slavic settling in the Balkans as no relevant migrations occur later to change the frequencies. The contribution of the Y chromosomes of peoples who settled in the Balkans before the Slavic expansion is the most likely explanation of the phenomenon according to the other study on Y-haplotypes, concluded by its two separate analyses because of the complicity of the methods tracing the alleles. The presence of two distinct genetic substrata in the genes of East-West and South Slavs would conclude that assimilation of indigenous populations by bearers of Slavic languages was a major mechanism of the spread of Slavic languages to the Balkan Peninsula. A signal at a low frequency among Balkan Slavs was detected that may have been inherited from the medieval Slavic settlers, but it was confirmed that this issue requires further investigation. Other studies detect a considerable connection between Bulgarians and North Slavs that is the result of migrations no earlier than 1500 years ago. The short genetic distance of South Slavs does not extend to populations throughout the whole Balkan Peninsula and they are differentiated from all Greek sub-populations that are not Macedonian Greek. The South Slavs share significantly fewer IBD segments for length classes with Greeks than with the group of East-West Slavs. Most of the East-West Slavs share as many such segments with the South Slavs as they share with the inter-Slavic populations between them. This might suggest Slavic gene flow across the wide area and physical boundaries such as the Carpathian Mountains, including Hungarians, Romanians and Gagauz. Bulgarians are also only modestly close to their eastern neighbours – the Anatolian Turks, suggesting the presence of certain geographic and cultural barriers between them. Despite various invasions of Altaic-speaking peoples in Europe, no significant impact from such Asian descent is recorded throughout southern and central Europe.

The genetic diversity among Bulgarians is the reason of more inherited deaseses The blood type of 21,568 Bulgarians is 37% A+ , 28% 0+, 14% B+, 7% AB+, 6+ A-, 4% 0-, 2% B-, 1% AB-, a distribution similar to the Sweden, the Czech Republic and Turkey.

Ancient DNA

A simplified model for recent demographic history of Europeans. The panels indicate a possible demographic scenario consistent with the observed signals. (A) Mesolithic HGs present in mainland Europe prior to the arrival of agriculture. (B) Initial spread of farming from the Middle East beginning from 7,000 YBP into SE Europe. (C) Expansion of farming to N Europe from SE European gene pool and establishment of main S-N gradient of genetic diversity. Wave of migration also reaches Sardinia. (D) Continuous population expansion and admixture with local HGs as well as additional migrations continues to shape genetic diversity in mainland Europe, but Sardinia remains mostly isolated (IBD: isolation by distance).

Despite the most common haplogroup among Bulgarians is I2a1b at 20%, 8000 years old hunter-gatherer samples of the same haplogroup came out genetically very distant from Bulgarian and Balkan individuals by an autosomal analysis of skeletal remains from Loschbour cave in Luxembourg.

Three Neolithic samples from Smyadovo culture were defined by mtDNA H and one late Enolithic by U52a2. Several mtDNA samples considered part of the Yamna culture came out haplogroups T2a1b1a, U2e1a, U5a1 and K.

Medieval gene flow within West Eurasia is shown by lines linking the best-matching donor group to the sources of admixture with recipient clusters (arrowhead). Linecolors represent the regional identity of the donor group, and line thickness represents the proportion of DNA coming from the donor group. Ranges of the dates (point estimates) for events involving sources most similar to selected donor groups are shown.

The Impact of Recent Admixture in West Eurasia.

Computing the frequency of common point mutations of several mtDNA Thracian remains from Romania has resulted that the Italian (7.9%), the Albanian (6.3%) and the Greek (5.8%) have shown a bias of closer genetic kinship with the Thracian individuals than the Romanian and Bulgarian individuals (4.2%), but it was noted that more mtDNA sequences from Thracian individuals are needed in order to perform an complex objective statistical analysis.

Four samples from Iron Age Bulgaria were studied, the official study confirmed only that the two are male and mtDNA of two individuals - U3b for the Svilengrad man and HV for the Stambolovo man, those men were from Thracian burial sites, some of them victims of a ritual sacrifice, and are dated at around 450-850 BC. Unofficial analysis of the raw data claims that the first one is positive for Y-DNA Haplogroup E-Z1919, who came out different from the rest by autosomal components. It also claims that according to the SNPs all the four samples came out male and also haplogroup J2-M410 was found among them, while another man's haplogroup came out negative for E, I and J and remained unknown but is likely R1, presumably R1b-Z2103.

13 samples from medieval Bulgarian sites were alleged as originally Bulgar, but there is no evidence for that. They were from a burial site from the Monastery of Mostich in Preslav, Nozharevo, Tuhovishte and most came out European mtDNA haplogroup H, including H1a2, H1r1, H1t1a1, H2a2a1 H5, H13a2c1, HV1, J, J1b1a1, T, T2 and U3 without any East Eurasian haplogroups found. It was shown a short genetic distance between these samples and modern Bulgarians. After at least 20 mediaval(10-14th century) mtDNA samples from Cedynia and Lednica in Poland, possibly Slavic, had been studied, the 855 sampled modern Bulgarians come out overally the closest group to these samples out of 20 other European nations and morever, they share the highest value of haplotypes with the medieval Polish population more than any other comapared nation does. Those medieval haplogroups included H, H1a, K1, K2, X2, X4, HV, J1b, R0a, HV0, H5a1a, N1b, T1a, J1b and W. The samples came out distant from modern Polish population, but nearest to the modern Bulgarian and Czech population.

20 medieval(9-12th century) samples from Slovakian sites Nitra Šindolka and 8 from Čakajovce were compared to modern population and Bulgarians, and Portuguese came out nearest to them by genetic distance, however all these came out distant to modern Slovak population.

Samples from three prehistoric European ancestor groups compared to modern peoples

Further evidence from ancient DNA, reconsiderations of mutation rates, and collateral evidence from autosomal DNA growth rates suggest that the major period of European population expansion occurred after the Holocene. Thus the current geographic spread and frequency of haplogroups has been continually shaped from the time of Palaeolithic colonization to beyond the Neolithic. This process of genetic shaping continued into recorded history, such as the Slavic migrations.

Recent studies of ancient DNA have revealed that European populations are largely descending from three ancestral groups. The first one are Paleolithic Siberians, the second one are Paleolithic European hunter-gatherers, and the third one are early farmers and later arrivals from the Near East and West Asia. According to this, Bulgarians are predominantly (~ 2/3) descending from early Neolithic farmers spreading the agriculture from Anatolia, and from West Asian Bronze Age invaders and cluster together with other Southern Europeans. Another of the admixture signals in that farmers involves some ancestry related to East Asians, with ~ 2% total Bulgarian ancestry proportion linking to a presence of nomadic groups in Europe, from the time of the Huns to that of the Ottomans. A third signal involves admixture between the North European group from one side and the West Asian - Early farmers' group from another side, at approximately the same time as the East Asian admixture, ca. 850 AD. This event may correspond to the expansion of Slavic language speaking people. The analysis documents the hunter-gatherer admixture in Bulgarians at a level from ca. 1/3.

According to Genographic Project's autosomal study called Your Regional Ancestry based on nine regional affiliations, the Bulgarians regional ancestry results are as follows: 47% Mediterranean and 20% southwest Asian impact, which reflect the strong influence of neolithic agriculturalists from the Fertile Crescent; 31% Northern European component that reflects Paleolithic hunter-gathers' ancestry; 2% Northeast Asian component which shows there have been some mixings with Asiatic inviders.

See also

• Genetic history of Europe

External links

• HLA-A_allele_frequencies_by_country
• HLA-DR_allele_frequencies_by_country
• HLA-DR Maps
• HLA-DRB1_DQA1_DQB1_polymorphism_in_the_Bulgarian_population