Mixed Race Studies

Building a Face, and a Case, on DNA

The New York Times
2015-02-23

Andrew Pollack

The police in Columbia, S.C.,  released this sketch of a possible suspect based on DNA left at the crime scene. Parabon NanoLabs, which made the image, has begun offering DNA phenotyping services to law enforcement agencies.

There were no known eyewitnesses to the murder of a young woman and her 3-year-old daughter four years ago. No security cameras caught a figure coming or going.

Nonetheless, the police in Columbia, S.C., last month released a sketch of a possible suspect. Rather than an artist’s rendering based on witness descriptions, the face was generated by a computer relying solely on DNA found at the scene of the crime.

It may be the first time a suspect’s face has been put before the public in this way, but it will not be the last. Investigators are increasingly able to determine the physical characteristics of crime suspects from the DNA they leave behind, providing what could become a powerful new tool for law enforcement.

Already genetic sleuths can determine a suspect’s eye and hair color fairly accurately. It is also possible, or might soon be, to predict skin color, freckling, baldness, hair curliness, tooth shape and age.

Computers may eventually be able to match faces generated from DNA to those in a database of mug shots. Even if it does not immediately find the culprit, the genetic witness, so to speak, can be useful, researchers say…

…Law enforcement authorities say that information about physical traits derived from DNA is not permitted in court because the science is not well established. Still, the prospect of widespread DNA phenotyping has unnerved some experts.

Duana Fullwiley, an associate professor of anthropology at Stanford, said that she worried that use of such images could contribute to racial profiling. She noted that Dr. Shriver developed his system by analyzing the DNA and faces of people with mixed West African and European ancestry.

“This leads to a technology that is better able to make faces that are African-American,” she said. The image produced in the South Carolina case, Dr. Fullwiley added, “was of a generic young black man.”

Dr. Shriver said he initially studied people of mixed European and African ancestry, many of them from Brazil, because that made the analysis easier. His more recent research has involved people of many different ethnicities, he said…

Read the entire article here.

Skin pigmentation, biogeographical ancestry and admixture mapping

Human Genetics
Volume 112, Issue 4 (April 2003)
pages 387-399

Mark D. Shriver, Professor of Anthropology
Pennsylvania State University

Esteban J. Parra
Department of Anthropology
University of Toronto at Mississauga

Sonia Dios
Department of Anthropology
Pennsylvania State University

Carolina Bonilla
Department of Anthropology
Pennsylvania State University

Heather Norton
Department of Anthropology
Pennsylvania State University

Celina Jovel
Department of Anthropology
Pennsylvania State University

Carrie Pfaff
Department of Anthropology
Pennsylvania State University

Cecily Jones
National Human Genome Center
Howard University, Washington, D.C.

Aisha Massac
National Human Genome Center
Howard University, Washington, D.C.

Neil Cameron
Takeway Media, London

Archie Baron
Takeway Media, London

Tabitha Jackson
Takeway Media, London

George Argyropoulos
Pennington Center for Biomedical Research, Baton Rouge, Louisiana

Li Jin
Department of Environmental Health
University of Cincinnati, Cincinnati, Ohio

Clive J. Hoggart
Department of Epidemiology and Population Health
London School of Hygiene and Tropical Medicine

Paul M. McKeigue
Department of Epidemiology and Population Health
London School of Hygiene and Tropical Medicine

Rick A. Kittles
National Human Genome Center
Howard University, Washington, D.C.

Ancestry informative markers (AIMs) are genetic loci showing alleles with large frequency differences between populations. AIMs can be used to estimate biogeographical ancestry at the level of the population, subgroup (e.g. cases and controls) and individual. Ancestry estimates at both the subgroup and individual level can be directly instructive regarding the genetics of the phenotypes that differ qualitatively or in frequency between populations. These estimates can provide a compelling foundation for the use of admixture mapping (AM) methods to identify the genes underlying these traits. We present details of a panel of 34 AIMs and demonstrate how such studies can proceed, by using skin pigmentation as a model phenotype. We have genotyped these markers in two population samples with primarily African ancestry, viz. African Americans from Washington D.C. and an African Caribbean sample from Britain, and in a sample of European Americans from Pennsylvania. In the two African population samples, we observed significant correlations between estimates of individual ancestry and skin pigmentation as measured by reflectometry (R²=0.21, P<0.0001 for the African-American sample and R²=0.16, P<0.0001 for the British African-Caribbean sample). These correlations confirm the validity of the ancestry estimates and also indicate the high level of population structure related to admixture, a level that characterizes these populations and that is detectable by using other tests to identify genetic structure. We have also applied two methods of admixture mapping to test for the effects of three candidate genes (TYR, OCA2, MC1R) on pigmentation. We show that TYR and OCA2 have measurable effects on skin pigmentation differences between the west African and west European parental populations. This work indicates that it is possible to estimate the individual ancestry of a person based on DNA analysis with a reasonable number of well-defined genetic markers. The implications and applications of ancestry estimates in biomedical research are discussed.

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Estimating Genetic Ancestry Proportions from Faces

PLoS ONE
Volume 4, Number 2, e4460 (February 2009)
8 pages
DOI: 10.1371/journal.pone.0004460

Yann C. Klimentidis
Department of Biostatistics
University of Alabama, Birmingham

Mark D. Shriver, Associate Professor of Anthropology
Pennsylvania State University

Ethnicity can be a means by which people identify themselves and others. This type of identification mediates many kinds of social interactions and may reflect adaptations to a long history of group living in humans. Recent admixture in the US between groups from different continents, and the historically strong emphasis on phenotypic differences between members of these groups, presents an opportunity to examine the degree of concordance between estimates of group membership based on genetic markers and on visually-based estimates of facial features. We first measured the degree of Native American, European, African and East Asian genetic admixture in a sample of 14 self-identified Hispanic individuals, chosen to cover a broad range of Native American and European genetic admixture proportions. We showed frontal and side-view photographs of the 14 individuals to 241 subjects living in New Mexico, and asked them to estimate the degree of NA admixture for each individual. We assess the overall concordance for each observer based on an aggregated measure of the difference between the observer and the genetic estimates. We find that observers reach a significantly higher degree of concordance than expected by chance, and that the degree of concordance as well as the direction of the discrepancy in estimates differs based on the ethnicity of the observer, but not on the observers’ age or sex. This study highlights the potentially high degree of discordance between physical appearance and genetic measures of ethnicity, as well as how perceptions of ethnic affiliation are context-specific. We compare our findings to those of previous studies and discuss their implications.

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Editorial: “Race Correction” in Pulmonary-Function Testing

New England Journal of Medicine
2010-07-07
DOI: 10.1056/NEJMe1005902

Paul D. Scanlon, M.D.
Division of Pulmonary and Critical Care Medicine
Mayo Clinic, Rochester, Minnesota

Mark D. Shriver, Ph.D.
Department of Anthropology
Pennsylvania State University, University Park (M.D.S.)

Tests of pulmonary function and radiographic imaging of the chest are the two key methods used in diagnostic evaluation of patients with pulmonary disease. Unlike blood pressure, acceptable normal values vary from person to person and from one demographic group to another. The first studies, in 1846, of spirometric assessment of forced vital capacity (FVC), the most basic pulmonary-function test, showed that normal values for vital capacity vary as a function of height and age. A few years later, it was shown that vital capacity was 6 to 12% lower in healthy black soldiers than in white or Native American soldiers. It has since become standard practice to calculate, for any individual patient, normal reference values for pulmonary-function tests on the basis of population-specific reference-value equations. In North America and Europe, where majority populations have primarily European ancestry, it is common practice to adjust reference values for persons of African or African-American ancestry, Hispanic ethnicity, or Asian ancestry—an adjustment termed “race correction” or “ethnic adjustment.”…

…There are practical problems with “race correction.” Self-identified race is the accepted standard for defining race, and no allowance is made for admixture (i.e., mixed parentage). The Asian-American adjustment factor is based on two studies with small numbers of participants representing a limited range of ages, ethnic groups, and socioeconomic status. A larger, recently published study showed that for Asian Americans, a correction factor of 0.88 is more accurate than 0.94.5 And little consideration has been given to the genetic diversity within Africa and within Asia.

Moreover, there is debate regarding the appropriateness of “race correction,” and a more general debate about the concepts of “race,” “ethnicity,” and “genetic ancestry” in medical research and treatment. Does race truly exist? If so, should it be taken into account, not only in pulmonary-function testing, but also in the broader practice of medicine and biomedical research?…

Read the entire editorial here.