Article

Mitochondrial Footprints of Human Expansions in Africa

School of Biological Sciences, Massey University, Palmerston North, New Zealand.
The American Journal of Human Genetics (Impact Factor: 10.93). 10/1997; 61(3):691-704. DOI: 10.1086/515503
Source: PubMed

ABSTRACT

mtDNA studies support an African origin for modern Eurasians, but expansion events within Africa have not previously been investigated. We have therefore analyzed 407 mtDNA control-region sequences from 13 African ethnic groups. A number of sequences (13%) were highly divergent and coalesced on the "mitochondrial Eve" in Africans. The remaining sequences also ultimately coalesced on this sequence but fell into four major clusters whose starlike phylogenies testify to demographic expansions. The oldest of these African expansions dates to approximately 60,000-80,000 years ago. Eurasian sequences are derived from essentially one sequence within this ancient cluster, even though a diverse mitochondrial pool was present in Africa at the time.

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    • "These lineages are derived from super-cluster L, which are further divided into the subgroups L1, L2, and L3. L3 represents the root of almost all mtDNA diversity outside Africa, differentiating into the major haplogroups, M and N (Watson et al., 1997). Europe, North America, and Australia have very high frequencies of haplogroup N sublineages, whereas in Asia, both M and N sublineages contribute differentially in different regions. "
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    • "should be further filtered after determining the correct genetic background (haplogroup), so that fixed evolutionary allelic variants may be promptly recognized. Indeed, human mitochondrial phylogeny is described by haplogroup classification based on clusters of closely related evolutionary haplotypes, defined by the pattern of genetic markers occurring in the entire mtDNA and reflecting the migration of human populations over continents (Watson et al. 1997; Balter 2011). Although clinicians are seldom familiar with the complexity of haplogroups, evolutionary and adaptive aspects should not be ignored in clinical studies, whereby the genetic association between haplogroup-defining variants and clinical phenotypes has been traced (Ghelli et al. 2009; Khan et al. 2013; Peng et al. 2013; Zhang et al. 2013). "
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