n human mitochondrial genetics, Haplogroup J is a human mitochondrial DNA (mtDNA) haplogroup. Haplogroup J derives from the haplogroup JT, which also gave rise to Haplogroup T. In his popular book The Seven Daughters of Eve, Bryan Sykes named the originator of this mtDNA haplogroup Jasmine. Within the field of medical genetics, certain polymorphisms specific to haplogroup J have been associated with Leber's hereditary optic neuropathy.
Origin[edit source | edit]
Around 45,000 years before present, a mutation took place in the DNA of a woman who lived in the Near East or Caucasus. Further mutations took place in the J line which can be identified as J1a1 (27,000 yrs ago), J2a (19,000 yrs ago), J2b2 (16,000 years ago), J2b3 (5,800 yrs ago), etc. Haplogroup J (along with ‘T’) MtDNA J & T colonised Europe from the Near East in the late Paleolithic & Mesolithic.
|Subclade||European coalescence time||Near East coalescence time|
|J1a1||27,300 years (± 8,000 years)||17,700 years (± 2,500 years)|
|J1a2||7,700 years (± 3,500 years)||—|
|J1b||5,000 years (± 2,200 years)||23,300 years (± 4,300 years)|
|J2a||19,200 years(± 6,900 years)||—|
|J2b1||—||15,000 years (± 5000 years)|
|J2b2||161,600* years (± 8,100 years)||16,000 years (± 5,700 years)|
|J2b3||5,800 years (± 2,900 years)||—|
*Typographical error from original source material as per time table describing the spread of populations given in the same study.
However, any statements concerning the geographic origin of this or any other haplogroup are highly speculative and considered by most population geneticists to be 'story telling' and outside the domain of science . Furthermore, inferring close associations between a haplogroup and a specific archaeological culture can be equally problematic.[by whom?]
Distribution[edit source | edit]
Average frequency of J Haplogroup as a whole is highest in the Near East (12%) followed by Europe (11%), Caucasus (8%) and North Africa (6%). Of the two main sub-groups, J1 takes up four-fifths of the total and is spread on the continent while J2 is more localised around the Mediterranean, Greece, Italy/Sardinia and Spain. In Pakistan, where West Eurasian lineages occur at frequencies of up to 50% in some ethno-linguistic groups, J1 averages around 5%, while J2 occurrence is very rare. Intriguingly, however, it is found amongst 9% of Kalash.
Within Europe, >2% frequency distribution of mtDNA J is as follows:
- J* = Ireland — 12%, England-Wales — 11%, Scotland — 9%, Orkney — 8%, Germany — 7%, Russia (European) — 7%, Iceland — 7%, Austria-Switzerland — 5%, Finland-Estonia — 5%, Spain-Portugal — 4%, France-Italy — 3%
- J1a = Austria-Switzerland — 3%
- J1b1 = Scotland — 4%
- J2 = France-Italy — 2%
- J2a = Homogenously spread in Europe. Absent in the nations around the Caucasus. Not known to be found elsewhere.
- J2b1 = Virtually absent in Europe. Found in diverse forms in the Near East.
Subclades[edit source | edit]
Tree[edit source | edit]
This phylogenetic tree of haplogroup J 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.
|[show]mtDNA HG "J" P-tree|
Genetic traits[edit source | edit]
It has been theorized[by whom?] that the uncoupling of oxidative phosphorylation related to SNPs which define mt-haplogroup J consequently produces higher body heat in the phenotype of mtDNA J individuals. This has been linked to selective pressure for the presence of the haplogroup in northern Europe, particularly Norway. J mtDNA has also been associated with HIV infected individuals displaying accelerated progression to AIDS and death. The T150C mutation, which is exclusive to but not definitive of, the J2 subclade of Haplogroup J may be part of a likely nuclearly controlled general machinery regarding the remodeling & replication of mtDNA. Controlling a remodeling which could accelerate mtDNA replication thus compensating for oxidative damage in mtDNA as well as functional deterioration occurring with old age related to it.