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Self-reported race/ethnicity in the age of genomic research: its potential impact on understanding health disparities.

Mersha TB, Abebe T - Hum. Genomics (2015)

Bottom Line: To better understand human genetic variation in the context of health disparities, we suggest using "ancestry" (or biogeographical ancestry) to describe actual genetic variation, "race" to describe health disparity in societies characterized by racial categories, and "ethnicity" to describe traditions, lifestyle, diet, and values.We also suggest using ancestry informative markers for precise characterization of individuals' biological ancestry.Understanding the sources of human genetic variation and the causes of health disparities could lead to interventions that would improve the health of all individuals.

View Article: PubMed Central - PubMed

Affiliation: Division of Asthma Research, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, University of Cincinnati, Cincinnati, OH, USA. tesfaye.mersha@cchmc.org.

ABSTRACT
This review explores the limitations of self-reported race, ethnicity, and genetic ancestry in biomedical research. Various terminologies are used to classify human differences in genomic research including race, ethnicity, and ancestry. Although race and ethnicity are related, race refers to a person's physical appearance, such as skin color and eye color. Ethnicity, on the other hand, refers to communality in cultural heritage, language, social practice, traditions, and geopolitical factors. Genetic ancestry inferred using ancestry informative markers (AIMs) is based on genetic/genomic data. Phenotype-based race/ethnicity information and data computed using AIMs often disagree. For example, self-reporting African Americans can have drastically different levels of African or European ancestry. Genetic analysis of individual ancestry shows that some self-identified African Americans have up to 99% of European ancestry, whereas some self-identified European Americans have substantial admixture from African ancestry. Similarly, African ancestry in the Latino population varies between 3% in Mexican Americans to 16% in Puerto Ricans. The implication of this is that, in African American or Latino populations, self-reported ancestry may not be as accurate as direct assessment of individual genomic information in predicting treatment outcomes. To better understand human genetic variation in the context of health disparities, we suggest using "ancestry" (or biogeographical ancestry) to describe actual genetic variation, "race" to describe health disparity in societies characterized by racial categories, and "ethnicity" to describe traditions, lifestyle, diet, and values. We also suggest using ancestry informative markers for precise characterization of individuals' biological ancestry. Understanding the sources of human genetic variation and the causes of health disparities could lead to interventions that would improve the health of all individuals.

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Related in: MedlinePlus

Map showing estimates of the percentage of European contribution to several African American communities throughout the US. The percentage of European contribution to several African American samples within the continental US varies tenfold, from 3.5% in the isolated Gullah-speaking Sea Islanders from South Carolina to 35% in Seattle. Reproduced from Parra [15].
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Fig1: Map showing estimates of the percentage of European contribution to several African American communities throughout the US. The percentage of European contribution to several African American samples within the continental US varies tenfold, from 3.5% in the isolated Gullah-speaking Sea Islanders from South Carolina to 35% in Seattle. Reproduced from Parra [15].

Mentions: Race and ethnicity are widely used interchangeably in population research and incorporate cultural, linguistic, biological, and geopolitical factors [11]. Although its use is primarily social, the term “race” is commonly defined in the scientific literature to refer to biological differences (such as skin color) between groups assumed to have different biogeographical ancestries or genetic makeup [11]. It is a “construct of human variability based on perceived differences in biology, physical appearance, and behavior” [12]. To the contrary, ethnicity is a complex multidimensional construct that reflects biological factors, geographical origins, historical influences, as well as shared customs, beliefs, and traditions among populations that may or may not have a common genetic origin [13]. For example, the Caucasian race contains such ethnicities as German, Irish, Spanish, and French each with their own culture, language, and tradition. Self-reported race/ethnicity is frequently used in epidemiological studies to assess an individual’s background origin. Often times, participants in the US are asked to specify a single race/ethnic group based on six categories: White, Black, Black Hispanic, White Hispanic, Asian, or other. Most questionnaires do not offer an opportunity for participants to choose multiple responses on their ancestral heritage. Most often, one family member declares for the rest, thus preventing detailed analysis of individuals with multiple (and differing) origins. A child of mixed parents (one black and one white) is socially classified as black, even though genetically, the child could just as easily be considered white (genotype 50/50). This classification was based on historical mandate of the “one-drop rule,” which stated that any individual with African ancestry would be considered a member of the Black race [14]. African and European ancestry in self-identified African Americans can vary wildly with proportions of European ancestry spanning the full range of variation, which can have significant impact on how we identify disease loci using genetics approach [13]. Parra [15] presents data showing that the percentage of European contribution to several African American communities within the continental US varies tenfold, from 3.5% in the isolated Gullah-speaking Sea Islanders from South Carolina to 35% in Seattle (Figure 1). Another example with broad ranges variation in admixture is the “Hispanic” or “Latino” population. The use of a single Hispanic or Latino ethnic category is insufficient for characterizing genetic background associated with Hispanics or Latinos because Hispanics have variable proportions of European, Native American, and African ancestry [16], as well as disease prevalence including asthma [17]. Mexican Americans, on average, have a higher proportion of Native American ancestry (ranging from 35% to 64%) but a lower proportion of African ancestry (ranging from 3% to 5%) than Puerto Ricans (Native American ancestry ranges between 12% and 15% and African ancestry ranges between 18% and 25%) [18-20] (Figure 2). Such higher proportion of African ancestry in Puerto Ricans could be the reason why the prevalence of asthma is the highest among Puerto Ricans (19.9%) and the lowest among Mexican Americans (6.5%). This phenomenon is referred to as the “Hispanic Paradox” [21].Figure 1


Self-reported race/ethnicity in the age of genomic research: its potential impact on understanding health disparities.

Mersha TB, Abebe T - Hum. Genomics (2015)

Map showing estimates of the percentage of European contribution to several African American communities throughout the US. The percentage of European contribution to several African American samples within the continental US varies tenfold, from 3.5% in the isolated Gullah-speaking Sea Islanders from South Carolina to 35% in Seattle. Reproduced from Parra [15].
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4307746&req=5

Fig1: Map showing estimates of the percentage of European contribution to several African American communities throughout the US. The percentage of European contribution to several African American samples within the continental US varies tenfold, from 3.5% in the isolated Gullah-speaking Sea Islanders from South Carolina to 35% in Seattle. Reproduced from Parra [15].
Mentions: Race and ethnicity are widely used interchangeably in population research and incorporate cultural, linguistic, biological, and geopolitical factors [11]. Although its use is primarily social, the term “race” is commonly defined in the scientific literature to refer to biological differences (such as skin color) between groups assumed to have different biogeographical ancestries or genetic makeup [11]. It is a “construct of human variability based on perceived differences in biology, physical appearance, and behavior” [12]. To the contrary, ethnicity is a complex multidimensional construct that reflects biological factors, geographical origins, historical influences, as well as shared customs, beliefs, and traditions among populations that may or may not have a common genetic origin [13]. For example, the Caucasian race contains such ethnicities as German, Irish, Spanish, and French each with their own culture, language, and tradition. Self-reported race/ethnicity is frequently used in epidemiological studies to assess an individual’s background origin. Often times, participants in the US are asked to specify a single race/ethnic group based on six categories: White, Black, Black Hispanic, White Hispanic, Asian, or other. Most questionnaires do not offer an opportunity for participants to choose multiple responses on their ancestral heritage. Most often, one family member declares for the rest, thus preventing detailed analysis of individuals with multiple (and differing) origins. A child of mixed parents (one black and one white) is socially classified as black, even though genetically, the child could just as easily be considered white (genotype 50/50). This classification was based on historical mandate of the “one-drop rule,” which stated that any individual with African ancestry would be considered a member of the Black race [14]. African and European ancestry in self-identified African Americans can vary wildly with proportions of European ancestry spanning the full range of variation, which can have significant impact on how we identify disease loci using genetics approach [13]. Parra [15] presents data showing that the percentage of European contribution to several African American communities within the continental US varies tenfold, from 3.5% in the isolated Gullah-speaking Sea Islanders from South Carolina to 35% in Seattle (Figure 1). Another example with broad ranges variation in admixture is the “Hispanic” or “Latino” population. The use of a single Hispanic or Latino ethnic category is insufficient for characterizing genetic background associated with Hispanics or Latinos because Hispanics have variable proportions of European, Native American, and African ancestry [16], as well as disease prevalence including asthma [17]. Mexican Americans, on average, have a higher proportion of Native American ancestry (ranging from 35% to 64%) but a lower proportion of African ancestry (ranging from 3% to 5%) than Puerto Ricans (Native American ancestry ranges between 12% and 15% and African ancestry ranges between 18% and 25%) [18-20] (Figure 2). Such higher proportion of African ancestry in Puerto Ricans could be the reason why the prevalence of asthma is the highest among Puerto Ricans (19.9%) and the lowest among Mexican Americans (6.5%). This phenomenon is referred to as the “Hispanic Paradox” [21].Figure 1

Bottom Line: To better understand human genetic variation in the context of health disparities, we suggest using "ancestry" (or biogeographical ancestry) to describe actual genetic variation, "race" to describe health disparity in societies characterized by racial categories, and "ethnicity" to describe traditions, lifestyle, diet, and values.We also suggest using ancestry informative markers for precise characterization of individuals' biological ancestry.Understanding the sources of human genetic variation and the causes of health disparities could lead to interventions that would improve the health of all individuals.

View Article: PubMed Central - PubMed

Affiliation: Division of Asthma Research, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, University of Cincinnati, Cincinnati, OH, USA. tesfaye.mersha@cchmc.org.

ABSTRACT
This review explores the limitations of self-reported race, ethnicity, and genetic ancestry in biomedical research. Various terminologies are used to classify human differences in genomic research including race, ethnicity, and ancestry. Although race and ethnicity are related, race refers to a person's physical appearance, such as skin color and eye color. Ethnicity, on the other hand, refers to communality in cultural heritage, language, social practice, traditions, and geopolitical factors. Genetic ancestry inferred using ancestry informative markers (AIMs) is based on genetic/genomic data. Phenotype-based race/ethnicity information and data computed using AIMs often disagree. For example, self-reporting African Americans can have drastically different levels of African or European ancestry. Genetic analysis of individual ancestry shows that some self-identified African Americans have up to 99% of European ancestry, whereas some self-identified European Americans have substantial admixture from African ancestry. Similarly, African ancestry in the Latino population varies between 3% in Mexican Americans to 16% in Puerto Ricans. The implication of this is that, in African American or Latino populations, self-reported ancestry may not be as accurate as direct assessment of individual genomic information in predicting treatment outcomes. To better understand human genetic variation in the context of health disparities, we suggest using "ancestry" (or biogeographical ancestry) to describe actual genetic variation, "race" to describe health disparity in societies characterized by racial categories, and "ethnicity" to describe traditions, lifestyle, diet, and values. We also suggest using ancestry informative markers for precise characterization of individuals' biological ancestry. Understanding the sources of human genetic variation and the causes of health disparities could lead to interventions that would improve the health of all individuals.

Show MeSH
Related in: MedlinePlus