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Use and Misuse of Race Information in
Genomic Research
Tesfaye B. Mersha, PhD
Assistant Professor
Division of Asthma Research
Cincinnati Children’s Hospital Medical Center
University of Cincinnati
Why race matters?
Every indicator of well-being shows disparities by race.
Race: physical markers (e.g. color)- it combines both
genetic and environmental determinant of health.
Ethnicity: Cultural markers- shared religion, race,
language, or place of origin.
Ancestry: Genetic markers- it is a statistical product
and refers to an individual’s genetic origin/background.
Outline
 Human origin and variation
 Race versus ancestry
 Does race exist, and matters?
 Admixed ancestry to study health disparities
 Ancestry and its measures
AncestrySNPminer…
 Discussion points
Potential questions about race and ancestry
Q1: Can scientist determine a person’s race by looking at his or
her DNA?
Q2: What does skin color tell you about a person?
Q3. Are there race-specific genes?
Q4. Can ancestry be a substitute for defining race or vice versa?
Q5. Is ancestry, rather than race, a better predictor of disease
risk?
Q5. Is knowing the patient’s race helps the doctor make an
accurate diagnosis?
Human Origin
KENYA
Lucy
The ‘First Human’ discovered in Ethiopia
Human Origin
We all are Ethiopians: Either living in Ethiopia or in recent exile!
http://www.academyll.org/wordpress/assets/Human-Migration-chart.pdf
Genetic variation in SNPs
ATTGCAATCCGTGG...ATCGAGCCA…TACGATTGCACGCCG…
ATTGCAAGCCGTGG...ATCTAGCCA…TACGATTGCAAGCCG…
ATTGCAAGCCGTGG...ATCTAGCCA…TACGATTGCAAGCCG…
ATTGCAATCCGTGG...ATCGAGCCA…TACGATTGCACGCCG…
ATTGCAAGCCGTGG...ATCTAGCCA…TACGATTGCAAGCCG…
How is variation distributed within and
between populations
15%
10-15%
Asian
85%
85-90%
Mersha, Human Genomics 2011
White
Comparison of completely sequenced individuals
 Watson and Venter share more alleles with Kim than with each other
European ancestry
Asian ancestry
James Watson
1,715,851
Seong-jin Kim
Craig Venter
 Geographic ancestry doesn’t correspond to genetic ancestry
•
The best way to know a person’s DNA is to study that person’s DNA
not his/her race or geographic ancestry.
Genome Res 2009, 19(9):1622-9
Genetic variation
race or phenotypic
variation
http://blogs.gonomad.com/readuponit/2007/07/tall-meets-short-in-china.html
Genetics and race
Who is Self-identified black, Latino, white?
Human diversity forms a gradient rather than discrete clusters
-6
-4
-2
0
2
https://www.youtube.com/watch?v=CRcex9NEJZE
44
4
Self-reported race and admixed ancestry
Broad peak for self-reported blacks due to admixture and absence of a single origin.
NEJM, 354;4 (2006)
Ancestry proportion of European and African Americans
across the United States
 23andMe- genetic testing company with over 800,000 customers
- about 80% of given their permission to participate in this study
 5,269 self-reported AAs and 148,789 EAs and >1/2 M SNPs
European Americans
African Americans
- EA with African ancestry are found at much higher frequencies in southern states.
- African ancestry among self-reported AAs are found highest in southern states,
especially South Carolina and Georgia.
The American Journal of Human Genetics 96 (1): 37-53, 2015.
Self-reported race is NOT a good proxy for ancestry
Wayne Joseph, Principal of a high school from southern California
Mr. Joseph considered himself as ‘black’ for 50
years but DNA PRINT Genomics Test finds out
that he has NO African ancestry.
https://chancellorfiles.wordpress.com/
Do human “races” exist?
Human populations have never been isolated long
enough to form true biological races.
If races are defined as “genetically discrete groups”,
then the answer is NO.
However, one can use race information to group
individuals into clusters and identify factors related
to health disparities.
Scientific American, December 2003
Misuse of race information in genomics
- Genotype information from self-reported races are
used to infer continental racial group:
- HapMap data: YRI genotype data from Nigeria to infer the
entire African continent.
- Race comparison in disease genetics without
controlling socio-environmental risk factors.
- Application of ancestry-related variants to
psychological and health related-traits
- Ancestry-related variants perceived as undesirable--health
insurance purpose!
 there is NO white gene or black gene!
Under what conditions should we use race?
• To identify societal construct such as health and
income disparities.
- unequal treatment due to actual/perceived race.
• To identify non-genetic causes of health disparities
(shared environmental risk factors).
- Environmental exposure such as traffic pollution,
dust, cigarette smoke, etc.
Prevalence of asthma in children in the U.S.
Asthma Prevalence (%)
20
15
10
5
0
Puerto Ricans
African Americans
European Americans
Mexican Americans
Asian Americans
Asthma prevalence is the highest in Puerto Rican and the lowest in Mexicans BUT
both are Latino/Hispanics?
Ancestry proportion: Mexicans vs. Puerto Ricans
Genome Biol. 2009;10(11):R132
Income differs by ancestry
Race can’t inform the racial gap in income
European Journal of Human Genetics (2008) 16, 762–765
Discussion points
• Human adaptation over years created population with
different skin color, hair texture---attribute to “race.”
• There is no black race gene or white race gene.
• Race and ancestry capture different information and can’t
substitute each other.
• Emphasizing group differences based ancestry could lead to
further disparities in health and healthcare outcomes
•
Both ancestry and race information should be considered to shade
light on heath disparities.
• Health disparities are the product of complex interactions of
racial/ethnic information, ancestry/genes and environments.
Acknowledgements
Funding: K01HL103165
Thank you
“The classic mirror reflects skin color; but the
DNA mirror reflects our common ancestors.”
Beatriz Marcheco, 2014