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Similar patterns of genetic variation present in diverse populations


Researchers have analyzed regions of the human genome in an ethnically diverse population and found essentially the same groups of single nucleotide polymorphisms, or SNPs, in most individuals. These groups of genetic variation—called haplotype blocks—have been passed down like heirlooms through successive generations from a common and small number of ancestors, according to the researchers.

Distribution of haplotypes across populations.

"When you look at the actual gene sequences, there are only a few ancestors that have given rise to the whole population," says David Altshuler, who led the study at the Whitehead/MIT Center for Genome Research in Cambridge, Massachusetts. The research is part of a larger project that aims to build a haplotype map of the human genome.

"This type of study could help identify the particular genetic variations that characterize disease," says Altshuler. Based on the data, the researchers estimate that a handful of haplotype blocks can account for the range of genetic variation in 90 percent of the population.

The researchers analyzed 51 haplotype blocks in the genomes of 275 individuals, including Africans, Asians, Caucasians, and African Americans. The genomic regions contained on average one SNP per 2,000 bases and covered .4 percent of the human genome. Although the study covered a fraction of the entire genome, the results provide a basis for understanding the patterns of genetic variation.

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Gabriel, S. B. et al. The structure of haplotype blocks in the human genome. Science Express. Published online May 23, 2002.

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