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When did North Africans acquire light skin color?
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[QUOTE]Originally posted by Djehuti: [QB] ^ We covered this [URL=http://www.egyptsearch.com/forums/ultimatebb.cgi?ubb=get_topic;f=8;t=010677]before[/URL]. [QUOTE]Originally posted by Djehuti: [qb] In fact, I've always questioned just how Eurasian is the SLC24A5 gene and for good reason.[/qb] [URL=https://www.nature.com/articles/5201659]Pigmentary Diversity: Identifying the genes causing human diversity[/URL] [i] SLC24A5 has a striking pattern of variation in human populations. A coding variant in the gene has previously been described as one of a set of ancestry-informative markers. The ancestral form encodes alanine at residue 111, whereas a derived allele encodes threonine. Alanine is present at this position in all known members of the SLC24 subfamily of proteins, suggesting the change to threonine has functional consequences. [b]The derived variant is universally present on all European chromosomes analysed, while chromosomes of *African* and Asian origin almost invariably carry the ancestral form.[/b] The population difference puts this variant in the top 0.01% of all variants studied. Furthermore, analysis of the HapMap Consortium data6 found that SLC24A5 was within a chromosomal region that has a striking reduction of heterozygosity of SNPs in the European population. In fact, at 150 kb it is the longest such segment identified in the genome.1 Such a long conserved homozygous haplotype indicates that there has been strong selection on a gene or genes, which has swept this segment across the population, and selection for homozygosity eliminated recombination between SNPs, which maintained a long haplotype. Another solute channel gene SLC45A2, or MATP, which is affected in human, mouse and fish pigmentary mutants, also shows strong association with ethnic ancestry. More than 90% of European chromosomes have a derived allele which is rare or absent in Africans. [b]The small number of people of European descent with the ancestral form of the gene appear to have significantly more pigmented skin[/b] and there is clear evidence for a selective sweep of the chromosomal segment around the SLC45A2 in the European population.[/i][/QUOTE] [/QB][/QUOTE]
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