This paper is very similar to the recent one in Human Genetics that identified the T/G-13915 SNP in a Sudanes population. Here, Tishkoff et al. identify two other SNPs in a population of Kenyans, Tanzanians and Sudanese. I wonder if there's some sort of rivalry going on between these two groups.
Convergent adaptation of human lactase persistence in Africa and Europe
Sarah A Tishkoff, Floyd A Reed, Alessia Ranciaro, Benjamin F Voight, Courtney C Babbitt, Jesse S Silverman, Kweli Powell, Holly M Mortensen, Jibril B Hirbo, Maha Osman, Muntaser Ibrahim, Sabah A Omar, Godfrey Lema, Thomas B Nyambo, Jilur Ghori, Suzannah Bumpstead, Jonathan K Pritchard, Gregory A Wray & Panos Deloukas
Nature Genetics Published online: 10 December 2006;
Abstract: 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. 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 from the LCT promoter in vitro. These SNPs originated on different haplotype backgrounds from the European C/T-13910 SNP and from each other. Genotyping across a 3-Mb region demonstrated haplotype homozygosity extending >2.0 Mb on chromosomes carrying C-14010, consistent with a selective sweep over the past 7,000 years. These data provide a marked example of convergent evolution due to strong selective pressure resulting from shared cultural traits—animal domestication and adult milk consumption.