Haplogroup U descends from a woman in the Haplogroup R (mtDNA) branch of the phylogenetic tree, who lived around 55,000 years ago.
Haplogroup U is found in 15% of Indian caste and 8% of Indian tribal populations. Haplogroup U is found in approximately 11% of native Europeans and is held as the oldest maternal haplogroup found in that region. In a 2013 study, all but one of the ancient modern human sequences from Europe belonged to maternal haplogroup U, thus confirming previous findings that haplogroup U was the dominant type of Mitochondrial DNA (mtDNA) in Europe before the spread of agriculture into Europe.
Haplogroup U is subdivided into Haplogroups U1-U9. Haplogroup K is a subclade of U8. The old age has led to a wide distribution of the descendant subgroups across Western Eurasia, North Africa, and South Asia. Some subclades of U have a more specific geographic range.
Haplogroup U1 is found at very low frequency throughout Europe. It is found more often in eastern Europe, Anatolia and the Near East. It is also found at low frequencies in India. Haplogroup U1 is a very ancient haplogroup, with an estimated age of about 32,000 years. U1 is found in the Svanetia region at 4.2%. Subclade U1a is found from India to Europe, but is extremely rare among the northern and Atlantic fringes of Europe including the British Isles and Scandinavia. Several examples in Tuscany have been noted. In India, U1a has been found in the Kerala region. U1b has a similar spread but is rarer than U1a. Some examples of U1b have been found among Jewish diaspora. Subclades U1a and U1b appear in equal frequency in eastern Europe.
The U1 subclades are: U1a (with deep-subclades U1a1, U1a1a, U1a1a1, U1a1b) and U1b.
DNA analysis of excavated remains now located at St. Augustine convent in Goa, India revealed the unique mtDNA subclade U1b, which is absent in India, but present in Georgia and surrounding regions. Since the genetic analysis corroborates archaeological and literary evidence, it is believed that the excavated remains belong to Queen Ketevan of Georgia.
Haplogroup U2 is most common in South Asia but is also found in low frequency in Central and West Asia, as well as in Europe as U2e (the Western Eurasian variety of U2 is named U2e). The overall frequency of U2 in South Asia is largely accounted for by the group U2i in India whereas haplogroup U2e, common in Europe, is entirely absent; given that these lineages diverged approximately 50,000-years-ago, these data have been interpreted as indicating very low maternal-line gene-flow between South Asia and Europe throughout this period. Approximately one half of the U mtDNAs in India belong to the Indian-specific branches of haplogroup U2 (U2i: U2a, U2b and U2c). While U2 is typically found in India, it is also present in the Nogais peoples, descendants of various Mongolic and Turkic tribes, who formed the Nogai Horde. Both U2 and U4 are found in the Kets and Nganasans, the indigenous inhabitants of the Yenisey River Basin and the Taimyr Peninsula.
The U2 subclades are: U2a, U2b, U2c, U2d, and U2e. With the India-specific subclades U2a, U2b, and U2c collectively referred to as U2i, the Eurasian haplogroup U2d appears to be a sister clade with the Indian haplogroup U2c, while U2e is considered a Western Eurasian-specific subclade.
Haplogroup U2 has been found in the remains of a 30,000-year-old hunter-gatherer from the Kostyonki, Voronezh Oblast in Central-South European Russia., in 4,800 to 4,000-year-old human remains from a Late NeolithicBell-Beaker site in Kromsdorf Germany, and in 2,000-year-old human remains from Bøgebjerggård in Southern Denmark. However, haplogroup U2 is rare in present day Scandinavians. The remains of a 2,000-year-old West Eurasian male of haplogroup U2e1 was found in the Xiongnu Cemetery of Northeast Mongolia.
Haplogroup U3 is defined by the HVR1transition A16343G. It is found at low levels throughout Europe (about 1% of the population), the Near East (about 2.5% of the population), and Central Asia (about 1% of the population). U3 is present in the Svan population from the Svaneti region (about 4.2% of the population) and among Lithuanian Romani, Polish Romani, and Spanish Romani populations (36-56%).
Haplogroup U3 has been found in 6400-year-old remains (U3a) discovered in the caves at Wadi El‐Makkukh near Jericho associated with the Chalcolithic period. Haplogroup U3 was already present in the West Eurasian gene pool around 6,000-years-ago and probably also its subclade U3a as well.
Haplogroup U4 has its origin in the Upper Palaeolithic, dating to approximately 25,000 years ago and has been implicated in the expansion of modern humans into Europe occurring before the Last Glacial Maximum. U4 is an ancient mitochondrial haplogroup and is relatively rare in modern populations. U4 is found in Europe with highest concentrations in Scandinavia and the Baltic states and is associated with the remnants of ancient European hunting-gatherers preserved in the indigenous populations of Siberia. U4 is found in Nganasans the indigenous inhabitants of the Taimyr Peninsula, in the Mansi (16.3%) an endangered people, and in the Ket people (28.9%) of the Yenisey River. U4 is also preserved in the Kalash people a unique tribe among the Indo-Aryan peoples of Pakistan where it attains its highest frequency of 34%.
Bryan Sykes provided this popular description for haplogroup U4: "The clan of Ulrike (German for Mistress of All) is not among the original 'Seven Daughters of Eve' clans, but with just under 2% of Europeans among its members, it has a claim to being included among the numerically important clans. Ulrike lived about 18,000 years ago in the cold refuges of the Ukraine at the northern limits of human habitation. Though Ulrike's descendants are nowhere common, the clan is found today mainly in the east and north of Europe with particularly high concentrations in Scandinavia and the Baltic states."
Haplogroup U4 is associated with ancient European hunter-gatherers and has been found in 7,200 to 6,000-year-old remains of the Pitted Ware culture in Gotland Sweden and in 4,400 to 3,800-year-old remains from the Damsbo site of the Danish Bell-Beaker culture. Remains identified as subclade U4a2 are associated with the Battle Axe culture which flourished 5,200 to 4,300 years ago in eastern and central Europe and encompassed most of continental northern Europe from the Volga River in the east to the Rhine River in the west. Mitochondrial DNA recovered from 3,500 to 3,300-year-old remains at the Bredtoftegård site in Denmark associated with the Nordic Bronze Age include haplogroup U4 with 16179T in its HVR1 indicative of subclade U4c1.
The age of U5 is estimated at 30-50,000 years. Approximately 11% of total Europeans and 10% of European-Americans are in haplogroup U5. In 'The Seven Daughters of Eve', this haplogroup, as well as Haplogroup U in general, is labelled 'Clan Ursula'. Haplogroup U5 is believed to be the oldest single branch of Haplogroup U, hence the sharing of the 'Ursula' designation by both groups. Because of that, it is widely believed that it was this branch who then interbred with another ancient European race, the Neanderthals themselves.
U5 has been found in human remains dating from the Mesolithic in England, Germany, Lithuania, Poland, Portugal, Russia, Sweden, France  and Spain.  Haplogroup U5 and its subclades U5a and U5b form the highest population concentrations in the far north, in Sami, Finns, and Estonians, but it is spread widely at lower levels throughout Europe. This distribution, and the age of the haplogroup, indicate individuals from this haplogroup were part of the initial expansion tracking the retreat of ice sheets from Europe around 10.000 years ago.
Haplogroup U5 is found also in small frequencies and at much lower diversity in the Near East and parts of northern Africa (areas with sizable U6 concentrations), suggesting back-migration of people from Europe to the south.
Mitochondrial haplogroup U5a has also been associated with HIV infected individuals displaying accelerated progression to AIDS and death.
U5 has polymorphisms in the locations of 3197 9477 13617 16192 16270
U5a arose around 20000 years ago and has polymorphisms in 14793 16256 ( + U5 polymorphisms).
U5a1 arose around 16000 years ago and has polymorphisms in 15218 16399( + U5a polymorphisms).
U5a1a arose around 15000 years ago and has polymorphisms in 1700 16192( + U5a1 polymorphisms).
U5a1a1 arose around 12000 years ago and has polymorphisms in 5495 15924( + U5a1a polymorphisms).
U5a1a1a arose around 600 AC  and has polymorphisms in 3816 (A3816G)(and has lost its polymorphism in 152 (backmutation) + U5a1a1 polymorphisms).
U5a1a1b arose around 3300 years ago  and has polymorphisms in 15110 (G15110A) (and has lost its polymorphism in 152 (backmutation) + U5a1a1 polymorphisms).
U5a1a1c has polymorphisms in 6905 (A6905G) 13015 (T13015C)+ U5a1a1 polymorphisms).
U5a1a1d arose around 0 AC  and has polymorphisms: G185A T204C T16362C (and has lost its polymorphism in 152 (backmutation) + U5a1a1 polymorphisms).
U5a1a2 arose around 10000 years ago  and has polymorphisms in 573.1C (deletion) 12346( + U5a1a polymorphisms).
U5a1a2a arose around 800 BC  and has polymorphisms in 5319 6629 6719( + U5a1a2 polymorphisms).
U5a1a2a1 arose around 400 AC  and has polymorphisms T6293C ( + U5a1a2a polymorphisms).
U5a1b arose around 8500 years ago and has polymorphisms in 9667 (A9667G) ( + U5a1 polymorphisms).
U5a1b1 arose around 7000 years ago and has polymorphisms in 16291 (C16291T) ( + U5a1b polymorphisms).
U5a1b1a arose around 5000 years ago  and has polymorphisms T4553C + U5a1b1 polymorphisms).
U5a1b1a1 arose around 500 AC and has polymorphisms C14574T + U5a1b1a polymorphisms).
U5a1b1b arose around 3000 years ago  and has polymorphisms in 8119 (T8119C)( + U5a1b1 polymorphisms).
U5a1b1c arose around 5000 years ago  and has polymorphisms in 9055 (G9055A)( + U5a1b1 polymorphisms).
U5a1b1c1 arose around 500 BC  and has polymorphisms in 1187 (T1187C)( + U5a1b1c polymorphisms).
U5a1b1c2 arose around 500 BC  and has polymorphisms in 3705 (G3705A)( + U5a1b1c polymorphisms).
U5a1b1d has polymorphisms in 12358 16093 ( + U5a1b1 polymorphisms).
U5a1b1e has polymorphisms in 12582 16192 16294 ( + U5a1b1 polymorphisms).
U5a1b2 has polymorphisms in 9632 ( + U5a1b polymorphisms).
U5a1b3 has polymorphisms in 16362 16428 ( + U5a1b polymorphisms).
U5a1c arose around 13000 years ago and has polymorphisms in 16320 ( + U5a1 polymorphisms).
U5a1c1 has polymorphisms in 195 13802 ( + U5a1c polymorphisms).
U5a1c2 has polymorphisms in 961 965.1C (deletion)( + U5a1c polymorphisms).
U5a1d arose around 19000 years ago and has polymorphisms in 3027 ( + U5a1 polymorphisms).
U5a1d1 has polymorphisms in 5263 13002 (to adenosine)( + U5a1d polymorphisms).
U5a1d2 has polymorphisms in 573.1C (deletion) 3552 (+ U5a1d polymorphisms).
U5a1d2a has polymorphisms in 195 4823 5583 16145 16189 (+ U5a1d2 polymorphisms).
U5a1e has polymorphisms in 3564 8610 ( + U5a1 polymorphisms).
U5a1f has polymorphisms in 6023 ( + U5a1 polymorphisms).
U5a2 arose around 14000 years ago and has polymorphisms in 16526( + U5a polymorphisms).
U5a2a arose around 6000 years ago and has polymorphisms in 13827 13928C 16114 16294 ( + U5a2 polymorphisms).
U5a2b arose around 8000 years ago and has polymorphisms in 9548 ( + U5a2 polymorphisms).
U5a2c arose around 13000 years ago and has polymorphisms in 10619( + U5a2 polymorphisms).
U5a2d and has polymorphisms in 7843 7978 8104 11107 16192! (backmutated in 16192 to the original Cambridge sequence) ( + U5a2 polymorphisms).
U5a2e and has polymorphisms in 151 152 3768 15289 16189 16311 16362 ( + U5a2 polymorphisms).
U5b arose around 24000 years ago and has polymorphisms in 150 7768 14182( + U5 polymorphisms).
U5b1 arose around 18000 years ago and has polymorphisms in 5656( + U5b polymorphisms).
U5b1a has polymorphisms in 5656 15097, 16189 and has lost its polymorphism in 7028 (backmutation)( + U5b1 polymorphisms).
U5b1b: has been found in Fulbe and Papel people in Guinea-Bissau and Yakuts people of northeastern Siberia. It arose around 11000 years ago and has polymorphisms in 12618 16189 ( + U5b1 polymorphisms).
U5b1c has polymorphisms in 5656 15191, 16189, 16311 + U5b1 polymorphisms) and arose about 13000 years ago.
U5b1d has polymorphisms in 5437 5656 and has lost its polymorphism in 16192 (backmutation)( + U5b1 polymorphisms).
U5b1e has polymorphisms in 152 2757 10283 12616 16189 and has lost its polymorphism in 16192 (backmutation)( + U5b1 polymorphisms) and arose about 6600 years ago. U5b1e is mainly seen in central Europe among Czechs, Slovaks, Hungarians and southern Russians.
U5b1g has polymorphisms in 151 228 573.1C 5656 10654 13759 14577 ( + U5b1 polymorphisms).
U5b2 arose around 24000 years ago and has polymorphisms in 1721 13637( + U5b polymorphisms).
U5b3: The subclade is found primary on the island of Sardinia.
Haplogroup U6 was named 'Ulla' by Bryan Sykes. It is common (around 10% of the people)  in North Africa (with a maximum of 29% in an Algerian Mozabites) and the Canary Islands (18% on average with a peak frequency of 50.1% in La Gomera). It is also found in the Iberian peninsula, where it has the highest diversity (10 out of 19 sublineages are only found in this region and not in Africa), Eastern Africa and occasionally in other locations.
U6 is thought to have entered North Africa around 30,000 years ago from the Near-East. In spite of the highest diversity of Iberian U6, Maca-Meyer argues for an Near East origin of this clade based on the highest diversity of subclade U6a in that region, where it would have arrived from West Asia. She estimates the age of U6 between 25,000 and 66,000 years BP. However U6 has its highest frequencies in North Africa and seems to be a specific haplogroup of that region.
Subgroup U6a reflects the first African expansion from the Maghrib returning to the east. Derivative clade U6a1 signals a posterior movement from East Africa back to the Maghrib and the Near East. This migration coincides with the probable Afroasiatic linguistic expansion. U6b and U6c clades, restricted to West Africa, had more localized expansions. U6b probably reached the Iberian Peninsula during the Capsian diffusion in North Africa. Two autochthonous derivatives of these clades (U6b1 and U6c1) indicate the arrival of North African settlers to the Canarian Archipelago in prehistoric times, most probably due to the Saharan desiccation. The absence of these Canarian lineages nowadays in Africa suggests important demographic movements in the western area of this Continent.
U6a: it is the most widespread (from Canary Islands and Iberian Peninsula to Syria, Ethiopia and Kenya) and has highest diversity in Eastern Africa. Estimated age: 24-27,500 BP. It has one major subclade:
U6a1: with similar distribution to U6a. Estimated age: 15-20,000 BP. Found in Brittany (France) at 4.5% frequency.
U6b: shows a more patched and western distribution. In the Iberian peninsula U6b is more frequent in the North (while U6a is in the South). It has also been found in low amounts in Morocco, Algeria, Senegal and Nigeria. Estimated age: 8,500-24,500 BP. It has one subclade:
U6b1: found only in the Canary Islands and in the Iberian peninsula. Estimated age: c. 6000 BP.
U6c: only found in Morocco and Canary Islands. Estimated age: 6,000-17,500 BP.
U6a and U6b share a common basal mutation (16219) that is not present in U6c.
Haplogroup U7 is considered a West Eurasian-specific mtDNA haplogroup, believed to have originated in the Black Sea area approximately 30,000-years-ago. In modern populations, U7 occurs at low frequency in the Caucasus, the western Siberian tribes, West Asia (about 4% in the Near East, 5% in Pakistan, and 10% in Iranians), South Asia (about 12% in Gujarat, the westernmost state of India, while for the whole of India its frequency stays around 2%), and the Vedda people of Sri Lanka where it reaches it highest frequency of 13.33% (subclade U7a). One third of the West Eurasian-specific mtDNAs found in India are in haplogroups U7, R2 and W. It is speculated that large-scale immigration carried these mitochondrial haplogroups into India.
The U7 subclades are: U7a (with deep-subclades U7a1, U7a2, U7a2a, U7a2b) and U7b.
Genetic analysis of individuals associated with the Late Hallstatt culture from Baden-Württemberg Germany considered to be examples of Iron Age “princely burials” included haplogroup U7. Haplogroup U7 was reported to have been found in 1200-year-old human remains (dating to around AD 834), in a woman believed to be from a Royal Clan, who was buried with the Viking Oseberg ship in Norway. Haplogroup U7 was found in 1000-year-old human remains (dating to around AD 1000-1250) in a Christian cemetery is Kongemarken Denmark. However, U7 is rare among present-day ethnic Scandinavians.
U8a: The Basques have the most ancestral phylogeny in Europe for the mitochondrial haplogroup U8a, a rare subgroup of U8, placing the Basque origin of this lineage in the Upper Palaeolithic. The lack of U8a lineages in Africa suggests that their ancestors may have originated from West Asia.
U8b: This clade has been found in Italy and Jordan.
See main article Haplogroup K (mtDNA). Haplogroup K makes up a sizeable fraction of European and West Asian mtDNA lineages. It is now known it is actually a subclade of haplogroup U8b'K, and is believed to have first arisen in northeastern Italy. Haplogroup UK shows some evidence of being highly protective against AIDS progression.
Haplogroup U9 is a rare clade in mtDNA phylogeny, characterized only recently in a few populations of Pakistan (Quintana-Murci et al. 2004). Its presence in Ethiopia and Yemen, together with some Indian-specific M lineages in the Yemeni sample, points to gene flow along the coast of the Arabian Sea. Haplogroups U9 and U4 share two common mutations at the root of their phylogeny. It is interesting that, in Pakistan, U9 occurs frequently only among the so-called “negroid Makrani” population. In this particular population, lineages specific to sub-Saharan Africans occur as frequently as 39%, which suggests that U9 lineages in Pakistan may have an African origin (Quintana-Murci et al. 2004). Regardless of which coast of the Arabian Sea may have been the origin of U9, its Ethiopian–southern Arabian–Indus Basin distribution hints that its diversification from U4 may have occurred in regions far away from the current area of the highest diversity and frequency of haplogroup U4—East Europe and western Siberia.
This phylogenetic tree of haplogroup U subclades is based on the paper by Mannis van Oven and Manfred Kayser Updated comprehensive phylogenetic tree of global human mitochondrial DNA variation and subsequent published research.
^, Eupedia: Prehistoric European DNA - mtDNA & Y-DNA Haplogroup Frequencies by Period
^, Ancient DNA Reveals Lack of Continuity between Neolithic Hunter-Gatherers and Contemporary Scandinavians, Malmstrom et al. 2009
^ ab, Genetic Diversity among Ancient Nordic Populations, Melchior et al 2010
^, Mitochondrial DNA Phylogeny in Eastern and Western Slavs, Malyarchuk et al. 2008
^, Ancestral Journeys: Ancient Western Eurasian DNA of the Copper and Bronze Ages, 2009
^, Genetic Diversity among Ancient Nordic Populations: Table 1. Nucleotide substitutions and mtDNA haplogroups assigned for individuals from the Neolithic site Damsbo (4,200 YBP) and the Early Bronze Age site Bredtoftegård (3,300–3,500 YBP), Melchior et al 2010
^, A Comprehensive hg U Mutation List, Ron Scott 2010
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^Malmstrom, H.et al. (November 2009). "Ancient DNA Reveals Lack of Continuity between Neolithic Hunter-Gatherers and Contemporary Scandinavians". Current Biology1: 1–5.
^Deguilloux, M-F.,et al. (January 2011). "News from the west: Ancient DNA from a French megalithic burial chamber". American Journal of Physical Anthropology144 (1): 108–18. doi:10.1002/ajpa.21376. PMID20717990.