Haplogroup A (Y-DNA)
This article needs to be updated.(March 2013)
|Possible time of origin||roughly 270,000 ybp|
|Possible place of origin||Africa|
|Descendants||A00, A0, A1, A2, A3, BT|
|Highest frequencies||macro-haplogroup subclades found among various populations in Northwest-Central Africa|
Haplogroup A is a human Y-chromosome DNA haplogroup. Unlike other Y-DNA clades, it is not defined by a specific mutation. It is the foundational haplogroup to all known patrilineal lineages carried by modern humans, and thus is the Y-chromosomal Adam.
Formerly also known as "clade I", bearers of extant sub-clades of haplogroup A are entirely found in Africa (or among descendants of recently extracted African populations), in contrast with the descendant haplogroup BT (clade II-X) bearers of which participated in the Out of Africa migration of anatomically modern humans.
The most basal subclades of haplogroup A are, by age of divergence, "A00", "A0", "A1" (also "A1a-T") and "A2-T". Haplogroup BT, ancestral to all non-African haplogroups, is a subclade of A2-T.
- 1 Origin
- 2 Distribution
- 3 Structure & geographical distribution
- 4 Nomenclature & taxonomical history
- 5 See also
- 6 References
- 7 External links
There are terminological difficulties,[clarification needed] but as "haplogroup A" has come to mean "the foundational haplogroup" (viz. of contemporary human population), haplogroup A is not defined by any mutation but refers to any haplogroup which is not descended from haplogroup BT, i.e. defined by the absence of the defining mutation of that group (M91). By this definition, haplogroup A includes all mutations that took place between the Y-MRCA (estimated at some 250 kya) and the mutation defining haplogroup BT (estimated at some 80–70 kya), including any extant subclades that may yet to be discovered.
Bearers of haplogroup A (i.e. absence of the defining mutation of haplogroup BT) have been found in Southern Africa's hunter-gatherer inhabited areas, especially among the San people. In addition, the most basal mitochondrial DNA lineages are also largely restricted to the San. However, the A lineages of Southern Africa are sub-clades of A lineages found in other parts of Africa, suggesting that A sub-haplogroups arrived in Southern Africa from elsewhere.
The two most basal lineages of haplogroup A, A0 and A1 (prior to the announcement of the discovery of haplogroup A00 in 2013), have been detected in West Africa, Northwest Africa and Central Africa. Cruciani et al. (2011) suggest that these lineages may have emerged somewhere in between Central and Northwest Africa. Scozzari et al. (2012) also supported "the hypothesis of an origin in the north-western quadrant of the African continent for the A1b [ i.e. A0 ] haplogroup".
The clade achieves its highest modern frequencies in the Bushmen hunter-gatherer populations of Southern Africa, followed closely by many Nilotic groups in Eastern Africa. However, haplogroup A's oldest sub-clades are exclusively found in Central-Northwest Africa, where it (and by extension the patrilinear ancestor of modern humans) is believed to have originated. Estimates of its time depth have varied greatly, at either close to 190 kya or close to 140 kya in separate 2013 studies, and with the inclusion of the previously unknown "A00" haplogroup to about 270 kya in 2015 studies.
The clade has also been observed at notable frequencies in certain populations in Ethiopia, as well as some Pygmy groups in Central Africa, and less commonly Niger–Congo speakers, who largely belong to the E1b1a clade. Haplogroup E in general is believed to have originated in Northeast Africa, and was later introduced to West Africa from where it spread around 5,000 years ago to Central, Southern and Southeastern Africa with the Bantu expansion. According to Wood et al. (2005) and Rosa et al. (2007), such relatively recent population movements from West Africa changed the pre-existing population Y chromosomal diversity in Central, Southern and Southeastern Africa, replacing the previous haplogroups in these areas with the now dominant E1b1a lineages. Traces of ancestral inhabitants, however, can be observed today in these regions via the presence of the Y DNA haplogroups A-M91 and B-M60 that are common in certain relict populations, such as the Mbuti Pygmies and the Khoisan.
|||Tsumkwe San (Namibia)||66%|
|||Khwe (South Africa)||12|
|||South Semitic (Ethiopia)||10|
In a composite sample of 3551 African men, Haplogroup A had a frequency of 5.4%. The highest frequencies of haplogroup A have been reported among the Khoisan of Southern Africa, Beta Israel, and Nilo-Saharans from Sudan.
Haplogroup A3b2-M13 has been observed in populations of northern Cameroon (2/9 = 22% Tupuri, 4/28 = 14% Mandara, 2/17 = 12% Fulbe) and eastern DRC (2/9 = 22% Alur, 1/18 = 6% Hema, 1/47 = 2% Mbuti).
Without testing for any subclade, haplogroup A Y-DNA has been observed in samples of several populations of Gabon, including 9% (3/33) of a sample of Baka, 3% (1/36) of a sample of Ndumu, 2% (1/46) of a sample of Duma, 2% (1/57) of a sample of Nzebi, and 2% (1/60) of a sample of Tsogo.
Haplogroup A3b2-M13 is common among the Southern Sudanese (53%), especially the Dinka Sudanese (61.5%). Haplogroup A3b2-M13 also has been observed in another sample of a South Sudanese population at a frequency of 45% (18/40), including 1/40 A3b2a-M171. Haplogroup A also has been reported in 14.6% (7/48) of an Amhara sample, 10.3% (8/78) of an Oromo sample, 13.6% (12/88) of another sample from Ethiopia, and 41% of a sample of the Beta Israel (Cruciani et al. 2002), and important percentages are also shared by Bantus in Kenya (14%, Luis et al. 2004) and Iraqw in Tanzania (3/43 = 7.0% (Luis et al. 2004) to 1/6 = 17% (Knight et al. 2003)).
The subclade A1 has been observed in Moroccan Berbers, while the subclade A3b2 has been observed in approximately 3% of Egyptian males.
One study has found haplogroup A in samples of various Khoisan-speaking tribes with frequency ranging from 10% to 70%. Surprisingly, this particular haplogroup was not found in a sample of the Hadzabe from Tanzania, a population traditionally considered an ancient remnant of Khoisans due to the presence of click consonants in their language.
Haplogroup A has been observed as A1 in European men in England. As A3b2, it has been observed with low frequency in Asia Minor, the Middle East, and some Mediterranean islands, among Aegean Turks, Sardinians, Palestinians, Jordanians, Yemenites, and Omanis. Without testing for any subclade, haplogroup A has been observed in a sample of Greeks from Mitilini on the Aegean island of Lesvos and in samples of Portuguese from southern Portugal, central Portugal, and Madeira. The authors of one study have reported finding what appears to be haplogroup A in 3.1% (2/65) of a sample of Cypriots, though they have not definitively excluded the possibility that either of these individuals may belong to haplogroup B or haplogroup C.
Structure & geographical distribution
- A00a (L1149, FGC25576, FGC26292, FGC26293, FGC27741)
- A00b (A4987/YP3666, A4981, A4982/YP2683, A4984/YP2995, A4985/YP3292, A4986, A4988/YP3731)
- A0 (CTS2809/L991) formerly A1b
- A1 (P305) formerly A1a-T, A0 and A1b
- A1a (M31)
- A1b (P108) formerly A2-T
- A1b1 (L419/PF712)
- A1b1a (L602, V50, V82, V198, V224)
- A1b1a1 (M14) formerly A2
- A1b1a1a (M6)
- A1b1a1a1 (P28) formerly A1b1a1a1b and A2b
- A1b1a1a (M6)
- A1b1a1 (M14) formerly A2
- A1b1b (M32) formerly A3
- A1b1b1 (M28) formerly A3a
- A1b1b2 (L427)
- A1b1b2a (M51/Page42) formerly A3b1
- A1b1b2a1 (P291)
- A1b1b2b (M13/PF1374) formerly A3b2
- A1b1b2b1 (M118)
- A1b1b2a (M51/Page42) formerly A3b1
- A1b1a (L602, V50, V82, V198, V224)
- BT (M91)
- A1b1 (L419/PF712)
Mendez et al. (2013) announced the discovery of a previously unknown haplogroup, for which they proposed the designator "A00". With an estimated age of around 270 kya, older than current estimates for the age of anatomically modern humans.
A00 is also sometimes known as "Perry's Y-chromosome" (or simply "Perry's Y"). This previously unknown haplogroup was discovered in 2012, in the Y chromosome of an African-American man, who had submitted his DNA for commercial genealogical analysis.) The subsequent discovery of other males belonging to A00 led to the reclassification of Perry's Y as A00a (A-L1149).
Researchers later found A00 was possessed by 11 Mbo males of Western Cameroon (out of a sample of 174 (6.32%). Subsequent research suggested that the overall rate of A00 was even higher among the Mbo, i.e. 9.3% (8 of 86) were later found to fall within A00b (A-A4987).
Further research in 2015 indicates that the modern population with the highest concentration of A00 is the Bangwa (or Nweh) of Cameroon (fr:Bangoua (peuple)): 27 of 67 (40.3%) samples were positive for A00a (L1149). One Bangwa individual did not fit into either A00a or A00b.
The subclade A1a (M31) has been found in approximately 2.8% (8/282) of a pool of seven samples of various ethnic groups in Guinea-Bissau, especially among the Papel-Manjaco-Mancanha (5/64 = 7.8%). In an earlier study published in 2003, Gonçalves et al. have reported finding A1a-M31 in 5.1% (14/276) of a sample from Guinea-Bissau and in 0.5% (1/201) of a pair of samples from Cabo Verde. The authors of another study have reported finding haplogroup A1a-M31 in 5% (2/39) of a sample of Mandinka from Senegambia and 2% (1/55) of a sample of Dogon from Mali. Haplogroup A1a-M31 also has been found in 3% (2/64) of a sample of Berbers from Morocco and 2.3% (1/44) of a sample of unspecified ethnic affiliation from Mali.
In 2007, seven men from Yorkshire, England sharing the unusual surname Revis were identified as being from the A1a (M31) subclade. It was discovered that these men had a common male-line ancestor from the 18th century, but no previous information about African ancestry was known.
The subclade A1b1a1a (M6; formerly A2 and A1b1a1a-M6) is typically found among Khoisan peoples. The authors of one study have reported finding haplogroup A-M6(xA-P28) in 28% (8/29) of a sample of Tsumkwe San and 16% (5/32) of a sample of !Kung/Sekele, and haplogroup A2b-P28 in 17% (5/29) of a sample of Tsumkwe San, 9% (3/32) of a sample of !Kung/Sekele, 9% (1/11) of a sample of Nama, and 6% (1/18) of a sample of Dama. The authors of another study have reported finding haplogroup A2 in 15.4% (6/39) of a sample of Khoisan males, including 5/39 A2-M6/M14/M23/M29/M49/M71/M135/M141(xA2a-M114) and 1/39 A2a-M114.
The subclade A1b1b1 (M28; formerly A3a) has only been rarely observed in the Horn of Africa. In 5% (1/20) of a mixed sample of speakers of South Semitic languages from Ethiopia, 1.1% (1/88) of a sample of Ethiopians, and 0.5% (1/201) in Somalis.
The subclade A1b1b2a (M51; formerly A3b1) occurs most frequently among Khoisan peoples (6/11 = 55% Nama, 11/39 = 28% Khoisan, 7/32 = 22% !Kung/Sekele, 6/29 = 21% Tsumkwe San, 1/18 = 6% Dama). However, it also has been found with lower frequency among Bantu peoples of Southern Africa, including 2/28 = 7% Sotho–Tswana, 3/53 = 6% non-Khoisan Southern Africans, 4/80 = 5% Xhosa, and 1/29 = 3% Zulu.
The subclade A1b1b2b (M13; formerly A3b2) is primarily distributed among Nilotic populations in East Africa and northern Cameroon. It is different from the A subclades that are found in the Khoisan samples and only remotely related to them (it is actually only one of many subclades within haplogroup A). This finding suggests an ancient divergence.
In Sudan, haplogroup A-M13 has been found in 28/53 = 52.8% of Southern Sudanese, 13/28 = 46.4% of the Nuba of central Sudan, 25/90 = 27.8% of Western Sudanese, 4/32 = 12.5% of local Hausa people, and 5/216 = 2.3% of Northern Sudanese.
In Ethiopia, one study has reported finding haplogroup A-M13 in 14.6% (7/48) of a sample of Amhara and 10.3% (8/78) of a sample of Oromo. Another study has reported finding haplogroup A3b2b-M118 in 6.8% (6/88) and haplogroup A3b2*-M13(xA3b2a-M171, A3b2b-M118) in 5.7% (5/88) of a mixed sample of Ethiopians, amounting to a total of 12.5% (11/88) A3b2-M13.
Haplogroup A-M13 also has been observed occasionally outside of Central and Eastern Africa, as in the Aegean Region of Turkey (2/30 = 6.7%), Yemenite Jews (1/20 = 5%), Egypt (4/147 = 2.7%, 3/92 = 3.3%), Palestinian Arabs (2/143 = 1.4%), Sardinia (1/77 = 1.3%, 1/22 = 4.5%), the capital of Jordan, Amman (1/101=1%), and Oman (1/121 = 0.8%).
Haplogroup A-M13 has been found among three Neolithic period fossils excavated from the Kadruka site in Sudan.
Nomenclature & taxonomical history
Prior to 2002, there were in academic literature at least seven naming systems for the Y-Chromosome Phylogenetic tree. This led to considerable confusion. In 2002, the major research groups came together and formed the Y-Chromosome Consortium (YCC). They published a joint paper that created a single new tree that all agreed to use. Later, a group of citizen scientists with an interest in population genetics and genetic genealogy formed a working group to create an amateur tree aiming at being above all timely. The table below brings together all of these works at the point of the landmark 2002 YCC Tree. This allows a researcher reviewing older published literature to quickly move between nomenclatures.
Initial sequencing of the human Y-chromosome had suggested that first split in the Y-Chromosome family tree occurred with the mutations that separated Haplogroup BT from Y-chromosomal Adam and haplogroup A more broadly. Subsequently, many intervening splits between Y-chromosomal Adam and BT, also became known.
A major shift in the understanding of the Y-DNA tree came with the publication of (Cruciani 2011). While the SNP marker M91 had been regarded as a key to identifying haplogroup BT, it was realised that the region surrounding M91 was a mutational hotspot, which is prone to recurrent back-mutations. Moreover, the 8T stretch of Haplogroup A represented the ancestral state of M91, and the 9T of haplogroup BT a derived state, which arose following the insertion of 1T. This explained why subclades A1b and A1a, the deepest branches of Haplogroup A, both possessed the 8T stretch. Similarly, the P97 marker, which was also used to identify haplogroup A, possessed the ancestral state in haplogroup A, but a derived state in haplogroup BT. Ultimately the tendency of M91 to back-mutate and (hence) its unreliability, led to M91 being discarded as a defining SNP by ISOGG in 2016. Conversely, P97 has been retained as a defining marker of Haplogroup BT.
|YCC 2002/2008 (Shorthand)||(α)||(β)||(γ)||(δ)||(ε)||(ζ)||(η)||YCC 2002 (Longhand)||YCC 2005 (Longhand)||YCC 2008 (Longhand)||YCC 2010r (Longhand)||ISOGG 2006||ISOGG 2007||ISOGG 2008||ISOGG 2009||ISOGG 2010||ISOGG 2011||ISOGG 2012|
The following research teams per their publications were represented in the creation of the YCC Tree.
- Human Y-chromosome DNA haplogroup
- Y-DNA haplogroups in populations of Sub-Saharan Africa
- Y-DNA haplogroups by ethnic group
- Y-DNA A subclades
- equivalent to an estimate of the age of the human Y-MRCA (see there); including the A00 lineage, Karmin et al. (2015) and Trombetta et al. (2015) estimate ages of 254,000 and 291,000 ybp, respectively.
- According to Cruciani et al. 2011, the most basal lineages have been detected in West, Northwest and Central Africa, suggesting plausibility for the Y-MRCA living in the general region of North-Central Africa". In a sample of 2204 African Y-chromosomes, 8 chromosomes belonged to either haplogroup A1b or A1a. Haplogroup A1a was identified in two Moroccan Berbers, one Fulbe and one Tuareg people from Niger. Haplogroup A1b was identified in three Bakola pygmies from Southern Cameroon and one Algerian Berber. Cruciani, Fulvio; Trombetta, Beniamino; Massaia, Andrea; Destro-Bisol, Giovanni; Sellitto, Daniele; Scozzari, Rosaria (2011). "A Revised Root for the Human Y Chromosomal Phylogenetic Tree: The Origin of Patrilineal Diversity in Africa". The American Journal of Human Genetics. 88 (6): 814–8. PMC . PMID 21601174. doi:10.1016/j.ajhg.2011.05.002. Scozzari et al. (2012) agreed with a plausible placement in "the north-western quadrant of the African continent" for the emergence of the A1b haplogroup: "the hypothesis of an origin in the north-western quadrant of the African continent for the A1b haplogroup, and, together with recent findings of ancient Y-lineages in central-western Africa, provide new evidence regarding the geographical origin of human MSY diversity". Scozzari R; Massaia A; D'Atanasio E; Myres NM; Perego UA; et al. (2012). Caramelli, David, ed. "Molecular Dissection of the Basal Clades in the Human Y Chromosome Phylogenetic Tree". PLOS ONE. 7 (11): e49170. PMC . PMID 23145109. doi:10.1371/journal.pone.0049170.
- A. Underhill, P. Shen, A.A. Lin, L. Jin, G. Passarino, W.H. Yang, E. Kauffman, B. Bonné-Tamir, J. Bertranpetit, P. Francalacci, et al. Y chromosome sequence variation and the history of human populations, Nat. Genet., 26 (2000), pp. 358–361
- Batini C, Ferri G, Destro-Bisol G, et al. (September 2011). "Signatures of the preagricultural peopling processes in sub-Saharan Africa as revealed by the phylogeography of early Y chromosome lineages". Mol. Biol. Evol. 28 (9): 2603–13. PMID 21478374. doi:10.1093/molbev/msr089. as PDF
- Cruciani F, Trombetta B, Massaia A, Destro-Bisol G, Sellitto D, Scozzari R (June 2011). "A revised root for the human Y chromosomal phylogenetic tree: the origin of patrilineal diversity in Africa". Am. J. Hum. Genet. 88 (6): 814–8. PMC . PMID 21601174. doi:10.1016/j.ajhg.2011.05.002.
- Scozzari R, Massaia A, D'Atanasio E, et al. (2012). "Molecular dissection of the basal clades in the human Y chromosome phylogenetic tree". PLOS ONE. 7 (11): e49170. PMC . PMID 23145109. doi:10.1371/journal.pone.0049170.
- Carina M. Schlebusch et al. (28 September 2017). "Southern African ancient genomes estimate modern human divergence to 350,000 to 260,000 years ago". Science. Retrieved 29 September 2017.
- Francalacci P, Morelli L, Angius A, Berutti R, Reinier F, Atzeni R, Pilu R, Busonero F, Maschio A, Zara I, Sanna D, Useli A, Urru MF, Marcelli M, Cusano R, Oppo M, Zoledziewska M, Pitzalis M, Deidda F, Porcu E, Poddie F, Kang HM, Lyons R, Tarrier B, Gresham JB, Li B, Tofanelli S, Alonso S, Dei M, Lai S, Mulas A, Whalen MB, Uzzau S, Jones C, Schlessinger D, Abecasis GR, Sanna S, Sidore C, Cucca F (2013). "Low-pass DNA sequencing of 1200 Sardinians reconstructs European Y-chromosome phylogeny". Science. 341 (6145): 565–569. PMID 23908240. doi:10.1126/science.1237947. Poznik GD, Henn BM, Yee MC, Sliwerska E, Euskirchen GM, Lin AA, Snyder M, Quintana-Murci L, Kidd JM, Underhill PA, Bustamante CD (2013). "Sequencing Y chromosomes resolves discrepancy in time to common ancestor of males versus females". Science. 341 (6145): 562–565. PMC . PMID 23908239. doi:10.1126/science.1237619. Cruciani et al. (2011) estimated 142 kya.
- "A recent bottleneck of Y chromosome diversity coincides with a global change in culture". Genome Research. 25 (4): 459–66. 2015. PMC . PMID 25770088. doi:10.1101/gr.186684.114.
- "Regional Differences in the Accumulation of SNPs on the Male-Specific Portion of the Human Y Chromosome Replicate Autosomal Patterns: Implications for Genetic Dating". PLOS ONE. 10 (7): e0134646. 2015. PMC . PMID 26226630. doi:10.1371/journal.pone.0134646.
- Abu-Amero KK, Hellani A, González AM, Larruga JM, Cabrera VM, Underhill PA (2009). "Saudi Arabian Y-Chromosome diversity and its relationship with nearby regions". BMC Genet. 10: 59. PMC . PMID 19772609. doi:10.1186/1471-2156-10-59.
- International Society of Genetic Genealogy. "Y-DNA Haplogroup Tree".
- Berniell-Lee G, Calafell F, Bosch E, et al. (July 2009). "Genetic and demographic implications of the Bantu expansion: insights from human paternal lineages". Mol. Biol. Evol. 26 (7): 1581–9. PMID 19369595. doi:10.1093/molbev/msp069.
- Rosa A, Ornelas C, Jobling MA, Brehm A, Villems R (2007). "Y-chromosomal diversity in the population of Guinea-Bissau: a multiethnic perspective". BMC Evol. Biol. 7: 124. PMC . PMID 17662131. doi:10.1186/1471-2148-7-124.
- Wood ET, Stover DA, Ehret C, et al. (July 2005). "Contrasting patterns of Y chromosome and mtDNA variation in Africa: evidence for sex-biased demographic processes". Eur. J. Hum. Genet. 13 (7): 867–76. PMID 15856073. doi:10.1038/sj.ejhg.5201408.
- Underhill PA, Passarino G, Lin AA, et al. (January 2001). "The phylogeography of Y chromosome binary haplotypes and the origins of modern human populations". Ann. Hum. Genet. 65 (Pt 1): 43–62. PMID 11415522. doi:10.1046/j.1469-1809.2001.6510043.x.
- 28/53 (Dinka, Nuer, and Shilluk), Hassan HY, Underhill PA, Cavalli-Sforza LL, Ibrahim ME (November 2008). "Y-chromosome variation among Sudanese: restricted gene flow, concordance with language, geography, and history" (PDF). Am. J. Phys. Anthropol. 137 (3): 316–23. PMID 18618658. doi:10.1002/ajpa.20876. Archived from the original (PDF) on 2009-03-04.
- Underhill PA, Shen P, Lin AA, et al. (November 2000). "Y chromosome sequence variation and the history of human populations". Nat. Genet. 26 (3): 358–61. PMID 11062480. doi:10.1038/81685.
- Cruciani F, Santolamazza P, Shen P, et al. (May 2002). "A back migration from Asia to sub-Saharan Africa is supported by high-resolution analysis of human Y-chromosome haplotypes". Am. J. Hum. Genet. 70 (5): 1197–214. PMC . PMID 11910562. doi:10.1086/340257.
- Shen P, Lavi T, Kivisild T, et al. (September 2004). "Reconstruction of patrilineages and matrilineages of Samaritans and other Israeli populations from Y-chromosome and mitochondrial DNA sequence variation". Hum. Mutat. 24 (3): 248–60. PMID 15300852. doi:10.1002/humu.20077.
- Cruciani F, Trombetta B, Sellitto D, et al. (July 2010). "Human Y chromosome haplogroup R-V88: a paternal genetic record of early mid Holocene trans-Saharan connections and the spread of Chadic languages". Eur. J. Hum. Genet. 18 (7): 800–7. PMC . PMID 20051990. doi:10.1038/ejhg.2009.231.
- Semino O, Santachiara-Benerecetti AS, Falaschi F, Cavalli-Sforza LL, Underhill PA (January 2002). "Ethiopians and Khoisan share the deepest clades of the human Y-chromosome phylogeny". Am. J. Hum. Genet. 70 (1): 265–8. PMC . PMID 11719903. doi:10.1086/338306.
- Luis JR, Rowold DJ, Regueiro M, et al. (March 2004). "The Levant versus the Horn of Africa: evidence for bidirectional corridors of human migrations". Am. J. Hum. Genet. 74 (3): 532–44. PMC . PMID 14973781. doi:10.1086/382286.
- King TE, Parkin EJ, Swinfield G, et al. (March 2007). "Africans in Yorkshire? The deepest-rooting clade of the Y phylogeny within an English genealogy". Eur. J. Hum. Genet. 15 (3): 288–93. PMC . PMID 17245408. doi:10.1038/sj.ejhg.5201771.
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- 16/26, Hassan et al. 2008
- Di Giacomo F, Luca F, Anagnou N, et al. (September 2003). "Clinal patterns of human Y chromosomal diversity in continental Italy and Greece are dominated by drift and founder effects". Mol. Phylogenet. Evol. 28 (3): 387–95. PMID 12927125. doi:10.1016/S1055-7903(03)00016-2.
- Gonçalves R, Freitas A, Branco M, et al. (July 2005). "Y-chromosome lineages from Portugal, Madeira and Açores record elements of Sephardim and Berber ancestry". Ann. Hum. Genet. 69 (Pt 4): 443–54. PMID 15996172. doi:10.1111/j.1529-8817.2005.00161.x.
- Capelli C, Redhead N, Romano V, et al. (March 2006). "Population structure in the Mediterranean basin: a Y chromosome perspective". Ann. Hum. Genet. 70 (Pt 2): 207–25. PMID 16626331. doi:10.1111/j.1529-8817.2005.00224.x.
- Krahn, Thomas. "YCC Tree". FTDNA. Archived from the original on 2011-07-26.
- Mendez, Fernando; Krahn, Thomas; Schrack, Bonnie; Krahn, Astrid-Maria; Veeramah, Krishna; Woerner, August; Fomine, Forka Leypey Mathew; Bradman, Neil; Thomas, Mark; Karafet, Tatiana M.; Hammer, Michael F. (7 March 2013). "An African American paternal lineage adds an extremely ancient root to the human Y chromosome phylogenetic tree" (PDF). American Journal of Human Genetics. 92 (3): 454–9. PMC . PMID 23453668. doi:10.1016/j.ajhg.2013.02.002. "Genotyping of a DNA sample that was submitted to a commercial genetic-testing facility demonstrated that the Y chromosome of this African American individual carried the ancestral state of all known Y chromosome SNPs. To further characterize this lineage, which we dubbed A00 (see Figure S1, available online, for proposed nomenclature)"; "We have renamed the basal branch in Cruciani et al.  as A0 (previously A1b) and refer to the presently reported lineage as A00. For deep branches discovered in the future, we suggest continuing the nomenclature A000, and so on."
- At first (Mendez et al. 2013) this was announced as "extremely ancient" (95% confidence interval 237–581 kya for the age of the Y-MRCA including the lineage of this postulated haplogroup).
- Albert Perry, a slave born in the United States between ca. 1819–1827, lived in York County, South Carolina. See FamilyTreeDNA, Haplogroup A chart
- Mendez et al. (2013), p. 455. Quote: "Upon searching a large pan-African database consisting of 5,648 samples from ten countries [...] we identified 11 Y chromosomes that were invariant and identical to the A00 chromosome at five of the six Y-STRs (2 of the 11 chromosomes carried DYS19-16, whereas the others carried DYS19-15). These 11 chromosomes were all found in a sample of 174 (~6.3%) Mbo individuals from western Cameroon (Figure 2). Seven of these Mbo chromosomes were available for further testing, and the genotypes were found to be identical at 37 of 39 SNPs known to be derived on the A00 chromosome (i.e., two of these genotyped SNPs were ancestral in the Mbo samples)".
- Which of Cameroon's peoples have members of haplogroup A00? // experiment.com update of funded research (Schrack/Fomine Forka) available online Quotes: We can now clearly see that with 40% A00, the Bangwa represent the epicentre of A00 in this region, and very possibly in the world. As I shared in the last Lab Note, we found that so far there are two main subgroups of A00, defined by different Y-SNP mutations, which, naturally, divide along ethnic lines: A00a among the Bangwa, and A00b among the Mbo. We also found the one Bangwa sample which didn't belong to either subgroup.".
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- "Y-Haplogroup A Phylogenetic Tree". March 2013. Retrieved 30 March 2013. (chart highlighting new branches added to the A phylotree in March 2013)
|Wikimedia Commons has media related to Haplogroup A of Y-DNA.|
- Family Tree DNA — Y-Haplogroup A Project
- African Haplogroup project at FTDNA
- Spread of Haplogroup A, from National Geographic
|Phylogenetic tree of human Y-chromosome DNA haplogroups [χ 1][χ 2]|
|A00||A0-T [χ 3]|
|A0||A1 [χ 4]|
|I||J||LT [χ 5]||K2|
|L||T [χ 6]||K2a [χ 7]||K2b [χ 8]||K2c||K2d||K2e [χ 9]|
|K2a1||K2b1 [χ 10]||P [χ 11]|
|NO||S [χ 12]||M [χ 13]||P1||P2|