Self-Reported Race and Genetic Admixture
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《新英格兰医药杂志》
To the Editor: The use of data on self-reported race in health research has been highly debated.1,2 For example, Burchard et al. recently argued that important information on disease susceptibility may be derived from the use of data on self-reported race,1 whereas Cooper et al.2 cited Wilson et al.,3 who argued that ethnic labels "are inaccurate representations of the inferred genetic clusters." Cooper et al., however, ignored later work4 that identified limitations in the analyses of Wilson et al. — specifically, inappropriate classification of groups, the use of a suboptimal model for cluster identification, and reliance on only 39 microsatellite markers for cluster analyses. With larger numbers of markers, it was shown that genetically distinct groups can be almost completely inferred from self-reported race.5
Despite advances in genetic analysis, clinicians and epidemiologists still disagree on the usefulness of race in clinical reporting. For example, sleep apnea is a condition that is more common in black children than in white children and is associated with distinct craniofacial features. Although some of the group differences may relate to environmental factors, it is unlikely that these would substantially influence facial structure and other relevant traits.
With support from a U.S. Public Health Service grant, we applied an admixture analysis6 to a sample population in Cleveland. Participants were clearly separated into unique groups with the use of this genetic approach. Whereas 93 percent of self-reported whites were classified as having predominantly European ancestry, less than 2 percent of blacks were so classified. Only 4 percent who reported their race as black had predominantly African ancestry; yet, the admixture proportions of this group made it possible to separate the population into two groups, in which 94 percent of self-reported blacks and 7 percent of self-reported whites were classified as being of mixed race (Figure 1). The sharp peak at the left in Figure 1 indicates that there are many persons who have no African ancestry (i.e., the values correspond to those of self-reported whites), and the broad peak at the right indicates that most blacks are of mixed race and do not originate from any single population. Thus, self-reported race and genetic ethnic ancestry appear to be highly correlated as a dichotomy, with those who self-report as being black comprising, as expected from historical and cultural practices in the United States, a broad range of African ancestry.
Figure 1. Frequency Histogram Showing the Percentage of African Ancestry in a Population Living in Cleveland.
Although the need for cautious interpretation of racial data is indisputable, genetic analyses show that self-reported race is informative for the classification of genetic clusters. Although self-reported blacks in the United States are largely of mixed race, genetic admixture analyses show clear differences between self-reported blacks and whites, indicating that self-reported race provides a means for identifying distinct groups. This information can be used potentially to elicit more efficient analyses of the genetic origins of disease and improved pharmacologic responses.
Moumita Sinha, M.Stat.
Emma K. Larkin, M.H.S.
Robert C. Elston, Ph.D.
Susan Redline, M.D., M.P.H.
Case Western Reserve University
Cleveland, OH 44106
susan.redline@case.edu
Supported in part by grants (HL46380, M01 RR00080, HV48141, RR03655, GM-28356, HL07567, and P30CAD43703) from the U.S. Public Health Service.
References
Burchard EG, Ziv E, Coyle N, et al. The importance of race and ethnic background in biomedical research and clinical practice. N Engl J Med 2003;348:1170-1175.
Cooper RS, Kaufman JS, Ward R. Race and genomics. N Engl J Med 2003;348:1166-1170.
Wilson JF, Weale ME, Smith AC, et al. Population genetic structure of variable drug response. Nat Genet 2001;29:265-269.
Risch N, Burchard E, Ziv E, Tang H. Categorization of humans in biomedical research: genes, race and disease. Genome Biol 2002;37:2007.1-2007.12.
Tang H, Quertermous T, Rodriguez B, et al. Genetic structure, self-identified race/ethnicity, and confounding in case-control association studies. Am J Hum Genet 2005;76:268-275.
Pritchard JK, Stephens M, Donnelly P. Inference of population structure using multilocus genotype data. Genetics 2000;155:945-959.
Despite advances in genetic analysis, clinicians and epidemiologists still disagree on the usefulness of race in clinical reporting. For example, sleep apnea is a condition that is more common in black children than in white children and is associated with distinct craniofacial features. Although some of the group differences may relate to environmental factors, it is unlikely that these would substantially influence facial structure and other relevant traits.
With support from a U.S. Public Health Service grant, we applied an admixture analysis6 to a sample population in Cleveland. Participants were clearly separated into unique groups with the use of this genetic approach. Whereas 93 percent of self-reported whites were classified as having predominantly European ancestry, less than 2 percent of blacks were so classified. Only 4 percent who reported their race as black had predominantly African ancestry; yet, the admixture proportions of this group made it possible to separate the population into two groups, in which 94 percent of self-reported blacks and 7 percent of self-reported whites were classified as being of mixed race (Figure 1). The sharp peak at the left in Figure 1 indicates that there are many persons who have no African ancestry (i.e., the values correspond to those of self-reported whites), and the broad peak at the right indicates that most blacks are of mixed race and do not originate from any single population. Thus, self-reported race and genetic ethnic ancestry appear to be highly correlated as a dichotomy, with those who self-report as being black comprising, as expected from historical and cultural practices in the United States, a broad range of African ancestry.
Figure 1. Frequency Histogram Showing the Percentage of African Ancestry in a Population Living in Cleveland.
Although the need for cautious interpretation of racial data is indisputable, genetic analyses show that self-reported race is informative for the classification of genetic clusters. Although self-reported blacks in the United States are largely of mixed race, genetic admixture analyses show clear differences between self-reported blacks and whites, indicating that self-reported race provides a means for identifying distinct groups. This information can be used potentially to elicit more efficient analyses of the genetic origins of disease and improved pharmacologic responses.
Moumita Sinha, M.Stat.
Emma K. Larkin, M.H.S.
Robert C. Elston, Ph.D.
Susan Redline, M.D., M.P.H.
Case Western Reserve University
Cleveland, OH 44106
susan.redline@case.edu
Supported in part by grants (HL46380, M01 RR00080, HV48141, RR03655, GM-28356, HL07567, and P30CAD43703) from the U.S. Public Health Service.
References
Burchard EG, Ziv E, Coyle N, et al. The importance of race and ethnic background in biomedical research and clinical practice. N Engl J Med 2003;348:1170-1175.
Cooper RS, Kaufman JS, Ward R. Race and genomics. N Engl J Med 2003;348:1166-1170.
Wilson JF, Weale ME, Smith AC, et al. Population genetic structure of variable drug response. Nat Genet 2001;29:265-269.
Risch N, Burchard E, Ziv E, Tang H. Categorization of humans in biomedical research: genes, race and disease. Genome Biol 2002;37:2007.1-2007.12.
Tang H, Quertermous T, Rodriguez B, et al. Genetic structure, self-identified race/ethnicity, and confounding in case-control association studies. Am J Hum Genet 2005;76:268-275.
Pritchard JK, Stephens M, Donnelly P. Inference of population structure using multilocus genotype data. Genetics 2000;155:945-959.