Convergent adaptation of human lactase persistence in Africa and Europe

@article{Tishkoff2007ConvergentAO,
  title={Convergent adaptation of human lactase persistence in Africa and Europe},
  author={Sarah A. Tishkoff and Floyd A. Reed and Alessia Ranciaro and Benjamin F. Voight and Courtney C. Babbitt and Jesse S Silverman and Kweli Powell and Holly M. Mortensen and Jibril B. Hirbo and Maha M. Osman and Muntaser E. Ibrahim and Sabah A. Omar and Godfrey Lema and Thomas Nyambo and Jilur Ghori and Suzannah J. Bumpstead and Jonathan K. Pritchard and Gregory A. Wray and Panos Deloukas},
  journal={Nature Genetics},
  year={2007},
  volume={39},
  pages={31-40}
}
A SNP in the gene encoding lactase (LCT) (C/T-13910) is associated with the ability to digest milk as adults (lactase persistence) in Europeans, but the genetic basis of lactase persistence in Africans was previously unknown. [] Key Result We conducted a genotype-phenotype association study in 470 Tanzanians, Kenyans and Sudanese and identified three SNPs (G/C-14010, T/G-13915 and C/G-13907) that are associated with lactase persistence and that have derived alleles that significantly enhance transcription…

Diversity of lactase persistence alleles in Ethiopia: signature of a soft selective sweep.

Genetic origins of lactase persistence and the spread of pastoralism in Africa.

The genetic variation of lactase persistence alleles in northeast Africa

TLDR
A 316bp region involved in regulating the expression of the LCT gene on chromosome 2 is sequenced, which encompasses five polymorphisms that have been associated with LP in Sudanese and South Sudanese populations, resulting in one of the greatest frequencies of LP-variants among all populations across the world.

Screening for lactase persistence associated genotypes in cattle domestication groups of northern India

TLDR
Evaluated the frequency of C/T 13910 SNP among cattle domesticating groups of northern India and it was observed that frequency of LP phenotype and that of T 13910 allele of LP was much higher in these groups compared to those with no history of cattle domestication.

The Onset of Lactase Persistence in Europe

TLDR
Various studies, from archaeology to population genetics, that have shed some light on the evolution of LP in Europe are discussed, suggesting that LP arose after dairying practices had developed.

Screening of variants for lactase persistence/non-persistence in populations from South Africa and Ghana

TLDR
Identification of the G/C-14010 variant in the Xhosa population, further confirms their genetic relatedness to other nomadic populations members that belong to the Bantu linguistic group in Tanzania and Kenya.

Several Different Lactase Persistence Associated Alleles and High Diversity of the Lactase Gene in the Admixed Brazilian Population

TLDR
The aims of this study were to identify polymorphisms in the MCM6 region associated with the lactase persistence phenotype and to determine the distribution of LCT gene haplotypes in 981 individuals from North, Northeast and South Brazil, which shows a high variability considering the number of L CT haplotypes observed.

Population genomics on the origin of lactase persistence in Europe and South Asia

TLDR
It is argued that the G to A mutation at rs182549 arose earlier than 23,000 years ago, the intermediate CA haplotype ancestral to the LP-related TA haplotype is still represented by samples from Tuscans, admixed Americans and South Asians, and the great majority of G to T mutated descendants have hitchhiked since the C to T mutation was favored by local selection.

Evidence of still-ongoing convergence evolution of the lactase persistence T-13910 alleles in humans.

TLDR
The data about global allelic haplotypes of the lactose-tolerance variant imply that the T(-13910) allele has been independently introduced more than once and that there is a still-ongoing process of convergent evolution of the LP alleles in humans.
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References

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TLDR
It is suggested that genetic drift was important in shaping the general pattern of non-African haplotype diversity, with recent directional selection in northern Europeans for the haplotype associated with lactase persistence.

Identification of a variant associated with adult-type hypolactasia

TLDR
A DNA variant, C/T−13910, completely associates with biochemically verified lactase non-persistence in Finnish families and a sample set of 236 individuals from four different populations, indicating that it is very old.

Genetics of Lactase Persistence and Lactose Intolerance

TLDR
A putative causal nucleotide change has been identified and occurs on the background of a very extended haplotype that is frequent in Northern Europeans, where lactase persistence is frequent and does not explain all the variation in lactase expression.

The Causal Element for the Lactase Persistence/ non‐persistence Polymorphism is Located in a 1 Mb Region of Linkage Disequilibrium in Europeans

TLDR
The existence of a one megabase stretch of linkage disequilibrium in the region of LCT is reported and it is shown that the –14 kb T allele and the –22 kb A allele both occur on the background of a very extended A haplotype.

Genetic evidence in support of a shared Eurasian-North African dairying origin

TLDR
The analyses suggest that contemporary Berber populations possess the genetic signature of a past migration of pastoralists from the Middle East and that they share a dairying origin with Europeans and Asians, but not with sub-Saharan Africans.

T-13910 DNA variant associated with lactase persistence interacts with Oct-1 and stimulates lactase promoter activity in vitro.

TLDR
The data suggest that the binding of Oct-1 to the T-13,910 variant directs increased lactase promoter activity and this might provide an explanation for the lactase persistence phenotype in the human population.

DID PERSISTENCE OF INTESTINAL LACTASE INTO ADULT LIFE ORIGINATE ON THE ARABIAN PENINSULA

Persistence of the intestinal enzyme lactase at high concentration into adult life (PL) occurs in some sections of the world's human population. For the mammalian kingdom that is an abnormal

Genetic signatures of strong recent positive selection at the lactase gene.

TLDR
It is estimated that strong selection occurred within the past 5,000-10,000 years, consistent with an advantage to lactase persistence in the setting of dairy farming; the signals of selection the authors observe are among the strongest yet seen for any gene in the genome.

The lactase persistence/non-persistence polymorphism is controlled by a cis-acting element.

TLDR
This work exploited known DNA 'marker' polymorphisms within the exons of the lactase gene to examine the expression of the individual lactase mRNA transcripts from persistent and non-persistent individuals in order to determine whether the regulation is in cis or trans.

Lactase persistence DNA variant enhances lactase promoter activity in vitro: functional role as a cis regulatory element.

TLDR
The DNA region of the C/T_(13910) lactase persistence/non-persistence variant functions in vitro as a cis element capable of enhancing differential transcriptional activation of the lactase promoter.
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