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A subtle key to human diversity
This week–
A subtle key to human diversity ANDY COGHLAN
CORBIS
ANY article containing the words “race” and “genetics” tends to be controversial, and any scientific study researching the links between these concepts more so. Now a study of people of European, Chinese and Japanese descent has revealed distinctive patterns of gene activity in the different groups. Critics of similar studies have long argued that it makes no scientific sense to link race and genetics, and not just because of the spectre of eugenics it evokes. The differences between the genomes of people of different ethnic origin are startlingly small, and what variation does exist is
–The same but different– 8 | NewScientist | 13 January 2007
greater between individuals than between ethnic groups. Though the new study’s findings do not fundamentally change this, geneticists agree that the details we are learning about how genes are expressed in different ethnic groups could have huge medical benefits. Richard Spielman at the University of Pennsylvania, Philadelphia, and colleagues examined gene activity in a particular type of white blood cell called a lymphoblastoid. These cells contain some 4000odd working genes when active in the body, out of the 23,000 or so genes in the entire human genome. Of 4197 genes the team studied, Europeans and Chinese
expressed 939 at significantly different levels, with Europeans and Japanese expressing 756 differently. Chinese and Japanese people expressed just 27 genes to significantly differing degrees. For most of these genes, the difference in activity between ethnic groups was less than twofold, though one gene, UGT2B17, was 22 times as active on average in European as in Asian carriers (Nature Genetics, DOI: 10.1038/ng1955). Spielman and his colleagues declined to discuss the implications with journalists, including those from New Scientist, but other geneticists say the results tally with what we know about the way the simple differences in DNA called single nucleotide polymorphisms or SNPs (pronounced “snips”) occur in different groups. In 11 genes Spielman studied in extra detail, a higher level of activity was associated with the presence of a SNP that switches the particular
gene on, providing more evidence of how tiny changes in the basic DNA code can significantly affect the expression of whole genes. “It all hangs together,” says Matt Hurles of the Wellcome Trust Sanger Institute in Cambridge, UK. “We knew that genetic variation is distributed unequally between populations and now we know it influences gene expression,” he says. “It’s nice to get this confirmation.” Stephen Scherer, a geneticist at the Hospital for Sick Children in Toronto, Canada, agrees. He wonders whether differing patterns of gene expression might also correlate with newly discovered differences in DNA known as copy-number variable (CNV) regions, in which genes are either missing or present as
“The details we are learning about gene expression in different ethnic groups could have huge medical benefits” multiple copies. One indication that this might be the case is that UGT2B17, the gene that is expressed most differently between the ethnic groups, is known to be missing in four out of five Asians compared to one in five Europeans. The next step, says Hurles, who co-discovered CNVs with Scherer and many others, is to test other cells to see if levels of expression vary as much in other tissues. A wider range of ethnic groups should also be tested, he says. Other geneticists stress the medical benefits that could flow from such research. For example, populations that differ in their susceptibility to diseases such as type 2 diabetes and high blood pressure also carry different SNPs, says Alkes Price of Harvard Medical School. So biologists might be able to link these SNP differences to the activities of specific genes and target those genes with drugs. “Although the results are not surprising, the ramifications for disease genetics are quite significant,” he says. ● www.newscientist.com
A subtle key to human diversity ANDY COGHLAN
CORBIS
ANY article containing the words “race” and “genetics” tends to be controversial, and any scientific study researching the links between these concepts more so. Now a study of people of European, Chinese and Japanese descent has revealed distinctive patterns of gene activity in the different groups. Critics of similar studies have long argued that it makes no scientific sense to link race and genetics, and not just because of the spectre of eugenics it evokes. The differences between the genomes of people of different ethnic origin are startlingly small, and what variation does exist is
–The same but different– 8 | NewScientist | 13 January 2007
greater between individuals than between ethnic groups. Though the new study’s findings do not fundamentally change this, geneticists agree that the details we are learning about how genes are expressed in different ethnic groups could have huge medical benefits. Richard Spielman at the University of Pennsylvania, Philadelphia, and colleagues examined gene activity in a particular type of white blood cell called a lymphoblastoid. These cells contain some 4000odd working genes when active in the body, out of the 23,000 or so genes in the entire human genome. Of 4197 genes the team studied, Europeans and Chinese
expressed 939 at significantly different levels, with Europeans and Japanese expressing 756 differently. Chinese and Japanese people expressed just 27 genes to significantly differing degrees. For most of these genes, the difference in activity between ethnic groups was less than twofold, though one gene, UGT2B17, was 22 times as active on average in European as in Asian carriers (Nature Genetics, DOI: 10.1038/ng1955). Spielman and his colleagues declined to discuss the implications with journalists, including those from New Scientist, but other geneticists say the results tally with what we know about the way the simple differences in DNA called single nucleotide polymorphisms or SNPs (pronounced “snips”) occur in different groups. In 11 genes Spielman studied in extra detail, a higher level of activity was associated with the presence of a SNP that switches the particular
gene on, providing more evidence of how tiny changes in the basic DNA code can significantly affect the expression of whole genes. “It all hangs together,” says Matt Hurles of the Wellcome Trust Sanger Institute in Cambridge, UK. “We knew that genetic variation is distributed unequally between populations and now we know it influences gene expression,” he says. “It’s nice to get this confirmation.” Stephen Scherer, a geneticist at the Hospital for Sick Children in Toronto, Canada, agrees. He wonders whether differing patterns of gene expression might also correlate with newly discovered differences in DNA known as copy-number variable (CNV) regions, in which genes are either missing or present as
“The details we are learning about gene expression in different ethnic groups could have huge medical benefits” multiple copies. One indication that this might be the case is that UGT2B17, the gene that is expressed most differently between the ethnic groups, is known to be missing in four out of five Asians compared to one in five Europeans. The next step, says Hurles, who co-discovered CNVs with Scherer and many others, is to test other cells to see if levels of expression vary as much in other tissues. A wider range of ethnic groups should also be tested, he says. Other geneticists stress the medical benefits that could flow from such research. For example, populations that differ in their susceptibility to diseases such as type 2 diabetes and high blood pressure also carry different SNPs, says Alkes Price of Harvard Medical School. So biologists might be able to link these SNP differences to the activities of specific genes and target those genes with drugs. “Although the results are not surprising, the ramifications for disease genetics are quite significant,” he says. ● www.newscientist.com