What Doctors Should Ignore

Posted in Articles, Health/Medicine/Genetics, Media Archive, United States on 2018-02-14 04:27Z by Steven

What Doctors Should Ignore

The New York Times
2017-12-08

Moises Velasquez-Manoff


Joan Wong

Science has revealed how arbitrary racial categories are. Perhaps medicine will abandon them, too.

Sickle cell anemia was first described in 1910 and was quickly labeled a “black” disease. At a time when many people were preoccupied with an imagined racial hierarchy, with whites on top, the disease was cited as evidence that people of African descent were inferior. But what of white people who presented with sickle cell anemia?

Doctors twisted themselves into knots trying to explain those cases away. White sickle cell patients must have mixed backgrounds, they contended — a black forebear they didn’t know about perhaps, or one they didn’t want to mention. Or maybe white patients’ symptoms didn’t stem from sickle cell anemia at all, but some other affliction. The bottom line was, the disease was “black,” so by definition white people couldn’t get it.

Today, scientists understand the sickle cell trait as an adaptation to malaria, not evidence of inferiority. One copy of the sickle cell trait protects against malaria. Having two can cause severe anemia and even death. Scientists also know that the trait is common outside Africa across the “malaria belt” — the Arabian Peninsula, India and parts of the Mediterranean Basin. And people historically considered white can, in fact, carry it. In the Greek town of Orchomenos, for example, the gene is more prevalent than it is among African-Americans.

We know all this, and yet the racialization of the disease, the idea that it occurs only in people of sub-Saharan African descent, persists. “When I talk to medical students, I get this all the time — ‘Sickle cell is a black trait,’ ” Michael Yudell, chairman of the department of community health and prevention at the Dornsife School of Public Health at Drexel University, told me.

That’s worrisome for many reasons, he says, chief among them that it may result in subpar medical care for some patients. Case in point: California’s universal blood disorder screening program has identified thousands of nonblack children with the sickle cell trait and scores with the disease — patients who, had doctors stuck to received “wisdom,” might have been missed.

Professor Yudell belongs to a growing chorus of scholars and researchers who argue that in science at least, we need to push past the race concept and, where possible, scrap it entirely. Professor Yudell and others contend that instead of talking about race, we should talk about ancestry (which, unlike “race,” refers to one’s genetic heritage, not innate qualities); or the specific gene variants that, like the sickle cell trait, affect disease risk; or environmental factors like poverty or diet that affect some groups more than others…

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Loci associated with skin pigmentation identified in African populations

Posted in Africa, Articles, Health/Medicine/Genetics, Media Archive on 2017-12-04 01:50Z by Steven

Loci associated with skin pigmentation identified in African populations

Science
2017-10-12
eaan8433
DOI: 10.1126/science.aan8433

Nicholas G. Crawford, Derek E. Kelly, Matthew E. B. Hansen, Marcia H. Beltrame, Shaohua Fan, Shanna L. Bowman, Ethan Jewett, Alessia Ranciaro, Simon Thompson, Yancy Lo, Susanne P. Pfeifer, Jeffrey D. Jensen, Michael C. Campbell, William Beggs, Farhad Hormozdiari, Sununguko Wata Mpoloka, Gaonyadiwe George Mokone, Thomas Nyambo, Dawit Wolde Meskel, Gurja Belay, Jake Haut, NISC Comparative Sequencing Program, Harriet Rothschild, Leonard Zon, Yi Zhou, Michael A. Kovacs, Mai Xu, Tongwu Zhang, Kevin Bishop, Jason Sinclair, Cecilia Rivas, Eugene Elliot, Jiyeon Choi, Shengchao A. Li, Belynda Hicks, Shawn Burgess, Christian Abnet, Dawn E. Watkins-Chow, Elena Oceana, Yun S. Song, Eleazar Eskin, Kevin M. Brown, Michael S. Marks, Stacie K. Loftus, William J. Pavan, Meredith Yeager, Stephen Chanock, Sarah Tishkoff

Despite the wide range of skin pigmentation in humans, little is known about its genetic basis in global populations. Examining ethnically diverse African genomes, we identify variants in or near SLC24A5, MFSD12, DDB1, TMEM138, OCA2 and HERC2 that are significantly associated with skin pigmentation. Genetic evidence indicates that the light pigmentation variant at SLC24A5 was introduced into East Africa by gene flow from non-Africans. At all other loci, variants associated with dark pigmentation in Africans are identical by descent in southern Asian and Australo-Melanesian populations. Functional analyses indicate that MFSD12 encodes a lysosomal protein that affects melanogenesis in zebrafish and mice, and that mutations in melanocyte-specific regulatory regions near DDB1/TMEM138 correlate with expression of UV response genes under selection in Eurasians.

Variation in epidermal pigmentation is a striking feature of modern humans. Human pigmentation is correlated with geographic and environmental variation (Fig. 1). Populations at lower latitudes have darker pigmentation than populations at higher latitudes, suggesting that skin pigmentation is an adaptation to differing levels of ultraviolet radiation (UVR) (1). Because equatorial regions receive more UVR than temperate regions, populations from these regions (including sub-Saharan Africans, South Asians, and Australo-Melanesians) have darker pigmentation (Fig. 1), which likely mitigates the negative impact of high UVR exposure such as skin cancer and folate degradation (1). In contrast, the synthesis of vitamin D3 in response to UVR, needed to prevent rickets, may drive selection for light pigmentation at high latitudes (1).

The basal layer of human skin contains melanocytes, specialized pigment cells that harbor subcellular organelles called melanosomes in which melanin pigments are synthesized and stored and then transferred to keratinocytes (2). Melanosome morphology and content differs between melanocytes that synthesize mainly eumelanins (black-brown pigments) or pheomelanins (pigments which range from yellow to reddish-brown) (3). Variation in skin pigmentation is due to the type and quantity of melanins generated, melanosome size, and the manner in which keratinocytes sequester and degrade melanins (4).

While over 350 pigmentation genes have been identified in animal models, only a subset of these genes have been linked to normal variation in humans (5). Of these, there is limited knowledge about loci that affect pigmentation in populations with African ancestry (6, 7).

Skin pigmentation is highly variable within Africa

To identify genes affecting skin pigmentation in Africa, we used a DSM II ColorMeter to quantify light reflectance from the inner arm as a proxy for melanin levels in 2,092 ethnically and genetically diverse Africans living in Ethiopia, Tanzania, and Botswana (table S1 and figs. S1 and S2) (8). Skin pigmentation levels vary extensively among Africans, with darkest pigmentation observed in Nilo-Saharan speaking pastoralist populations in Eastern Africa and lightest pigmentation observed in San hunter-gatherer populations from southern Africa (Fig. 2 and table S1)…

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Taking race out of human genetics and memetics: We can’t achieve one without achieving the other

Posted in Articles, Health/Medicine/Genetics, Media Archive, Politics/Public Policy, Social Science on 2016-03-24 01:52Z by Steven

Taking race out of human genetics and memetics: We can’t achieve one without achieving the other

OUPblog: Oxford University Press’s Academic Insights for the Thinking World
2016-03-23

Carlos Hoyt

Carlos Hoyt explores race, racial identity and related issues as a scholar, teacher, psychotherapist, parent, and racialized member of our society, interrogating master narratives and the dominant discourse on race with the goal of illuminating and virtuously disrupting the racial worldview. Carlos holds teaching positions at Wheelock College, Simmons College, and Boston University in Boston Massachusetts, and has authored peer-reviewed articles on spirituality in social work practice and the pedagogy of the definition of racism. He is the author of The Arc of a Bad Idea: Understanding and Transcending Race, published by Oxford University Press.

Acknowledging that they are certainly not the first to do so, four scientists, Michael Yudell, Dorothy Roberts, Rob Desalle, and Sarah Tishkoff recently called for the phasing out of the use of the concept/term “race” in biological science.

Because race is an irredeemably nebulous, confused, and confusing social construct, the authors advocate for replacing it with “ancestry.” “Ancestry,” they say, is a “process-based” concept that encourages one to seek information about genomic heritage, while race is a “patternbased” concept that induces one to organize individuals into preconceived hierarchical groupings based on shifting, murky, and contradictory combinations of appearance, geography, ability, worth, and the like.

If biological science seeks and relies on valid and maximally precise population level comparisons between groups, and race is an irrefutably imprecise proxy for consistent and concordant biological/genetic comparison, then of course we should stop using it in biology and switch over to “ancestry,” “genetic heritage,” or some other term that actually gets at what’s real, reliable, and useful. It doesn’t feel like a rocket-science proposition. And yet biological science hasn’t been able to heed the call and make the shift. And I sadly forecast that the shift won’t soon – or ever – be made – unless and until we take the step that even the well-meaning authors of this call for stop short of taking…

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Is It Time To Stop Using Race In Medical Research?

Posted in Articles, Health/Medicine/Genetics, Interviews, Media Archive, Politics/Public Policy, Social Science on 2016-02-06 19:47Z by Steven

Is It Time To Stop Using Race In Medical Research?

Shots: Health News from NPR
National Public Radio
2016-02-05

Angus Chen

Genetics researchers often discover certain snips and pieces of the human genome that are important for health and development, such as the genetic mutations that cause cystic fibrosis or sickle cell anemia. And scientists noticed that genetic variants are more common in some races, which makes it seem like race is important in genetics research.

But some researchers say that we’ve taken the concept too far. To find out what that means, we’ve talked to two of the authors of an article published Thursday in the journal Science. Sarah Tishkoff is a human population geneticist and a professor at the University of Pennsylvania. Dorothy Roberts is a legal scholar, sociologist and a professor at the University of Pennsylvania’s Africana Studies department. This interview has been edited for length and clarity…

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Taking race out of human genetics

Posted in Articles, Health/Medicine/Genetics, Media Archive, Politics/Public Policy, Social Science on 2016-02-06 17:35Z by Steven

Taking race out of human genetics

Science
Volume 351, Issue 6273 (2016-02-05)
pages 564-565
DOI: 10.1126/science.aac4951

Michael Yudell, Associate Professor
Dornsife School of Public Health Department of Community Health and Prevention
Drexel University, Philadelphia, Pennsylvania

Dorothy Roberts, George A. Weiss University Professor of Law and Sociology and the Raymond Pace and Sadie Tanner Mossell Alexander Professor of Civil Rights
University of Pennsylvania

Rob DeSalle, Curator, Molecular Systematics; Principal Investigator, SICG Genomics Lab; Professor, Richard Gilder Graduate School
American Museum of Natural History, New York, New York

Sarah Tishkoff, David and Lyn Silfen University Professor in Genetics and Biology
University of Pennsylvania

In the wake of the sequencing of the human genome in the early 2000s, genome pioneers and social scientists alike called for an end to the use of race as a variable in genetic research (1, 2). Unfortunately, by some measures, the use of race as a biological category has increased in the postgenomic age (3). Although inconsistent definition and use has been a chief problem with the race concept, it has historically been used as a taxonomic categorization based on common hereditary traits (such as skin color) to elucidate the relationship between our ancestry and our genes. We believe the use of biological concepts of race in human genetic research—so disputed and so mired in confusion—is problematic at best and harmful at worst. It is time for biologists to find a better way.

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