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Fazzari V, Moo-Choy A, Panoyan MA, Abbatangelo CL, Polimanti R, Novroski NM, Wendt FR. Multi-ancestry tandem repeat association study of hair colour using exome-wide sequencing. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.24.581865. [PMID: 38464141 PMCID: PMC10925195 DOI: 10.1101/2024.02.24.581865] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
Hair colour variation is influenced by hundreds of positions across the human genome but this genetic contribution has only been narrowly explored. Genome-wide association studies identified single nucleotide polymorphisms (SNPs) influencing hair colour but the biology underlying these associations is challenging to interpret. We report 16 tandem repeats (TRs) with effects on different models of hair colour plus two TRs associated with hair colour in diverse ancestry groups. Several of these TRs expand or contract amino acid coding regions of their localized protein such that structure, and by extension function, may be altered. We also demonstrate that independent of SNP variation, these TRs can be used to great an additive polygenic score that predicts darker hair colour. This work adds to the growing body of evidence regarding TR influence on human traits with relatively large and independent effects relative to surrounding SNP variation.
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Hohl DM, González R, Di Santo Meztler GP, Patiño-Rico J, Dejean C, Avena S, Gutiérrez MDLÁ, Catanesi CI. Applicability of the IrisPlex system for eye color prediction in an admixed population from Argentina. Ann Hum Genet 2022; 86:297-327. [PMID: 35946314 DOI: 10.1111/ahg.12480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 07/07/2022] [Accepted: 07/11/2022] [Indexed: 11/29/2022]
Abstract
Eye color prediction based on an individual's genetic information is of interest in the field of forensic genetics. In recent years, researchers have studied different genes and markers associated with this externally visible characteristic and have developed methods for its prediction. The IrisPlex represents a validated tool for homogeneous populations, though its applicability in populations of mixed ancestry is limited, mainly regarding the prediction of intermediate eye colors. With the aim of validating the applicability of this system in an admixed population from Argentina (n = 302), we analyzed the six single nucleotide variants used in that multiplex for eye color and four additional SNPs, and evaluated its prediction ability. We also performed a genotype-phenotype association analysis. This system proved to be useful when dealing with the extreme ends of the eye color spectrum (blue and brown) but presented difficulties in determining the intermediate phenotypes (green), which were found in a large proportion of our population. We concluded that these genetic tools should be used with caution in admixed populations and that more studies are required in order to improve the prediction of intermediate phenotypes.
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Affiliation(s)
- Diana María Hohl
- Laboratorio de Diversidad Genética, Instituto Multidisciplinario de Biología Celular IMBICE (CONICET-UNLP-CIC), La Plata, Buenos Aires, Argentina
| | - Rebeca González
- Laboratorio de Diversidad Genética, Instituto Multidisciplinario de Biología Celular IMBICE (CONICET-UNLP-CIC), La Plata, Buenos Aires, Argentina
| | - Gabriela Paula Di Santo Meztler
- Centro de Investigación de Proteínas Vegetales (CIPROVE-Centro Asociado CICPBA-UNLP), Depto. de Cs. Biológicas, Facultad de Cs. Exactas, Universidad Nacional de La Plata (UNLP), La Plata, Buenos Aires, Argentina
| | - Jessica Patiño-Rico
- Centro de Ciencias Naturales, Ambientales y Antropológicas, Universidad Maimónides, Buenos Aires, Argentina
| | - Cristina Dejean
- Centro de Ciencias Naturales, Ambientales y Antropológicas, Universidad Maimónides, Buenos Aires, Argentina.,Universidad de Buenos Aires, Facultad de Filosofía y Letras, Instituto de Ciencias Antropológicas (ICA), Sección Antropología Biológica, Buenos Aires, Argentina
| | - Sergio Avena
- Centro de Ciencias Naturales, Ambientales y Antropológicas, Universidad Maimónides, Buenos Aires, Argentina.,Consejo Nacional de Investigaciones Científicas y Técnicas CONICET, Buenos Aires, Argentina
| | - María De Los Ángeles Gutiérrez
- Centro de Investigaciones del Medioambiente CIM, Facultad de Ciencias Exactas-CONICET, Universidad Nacional de La Plata, La Plata, Buenos Aires, Argentina
| | - Cecilia Inés Catanesi
- Laboratorio de Diversidad Genética, Instituto Multidisciplinario de Biología Celular IMBICE (CONICET-UNLP-CIC), La Plata, Buenos Aires, Argentina.,Consejo Nacional de Investigaciones Científicas y Técnicas CONICET, Buenos Aires, Argentina.,Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, La Plata, Buenos Aires, Argentina
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Investigating the genetic architecture of eye colour in a Canadian cohort. iScience 2022; 25:104485. [PMID: 35712076 PMCID: PMC9194134 DOI: 10.1016/j.isci.2022.104485] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Revised: 04/18/2022] [Accepted: 05/24/2022] [Indexed: 11/24/2022] Open
Abstract
Eye color is highly variable in populations with European ancestry, ranging from low to high quantities of melanin in the iris. Polymorphisms in the HERC2/OCA2 locus have the largest effect on eye color in these populations, although other genomic regions also influence eye color. We performed genome-wide association studies of eye color in a Canadian cohort of European ancestry (N = 5,641) and investigated candidate causal variants. We uncovered several candidate causal signals in the HERC2/OCA2 region, whereas other loci likely harbor a single causal signal. We observed colocalization of eye color signals with the expression or methylation profiles of cultured primary melanocytes. Genetic correlations of eye and hair color suggest high genome-wide pleiotropy, but locus-level differences in the genetic architecture of both traits. Overall, we provide a better picture of the polymorphisms underpinning eye color variation, which may be a consequence of specific molecular processes in the iris melanocytes. Genome-wide association studies of eye color in 5,641 participants Multiple independent candidate causal variants were identified across HERC2/OCA2 Single candidate causal variants observed on or near IRF4, SLC24A4, TYR, and TYRP1 Colocalization of eye color signals with expression and methylation profiles
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Norton HL. Variation in pulse oximetry readings: melanin, not ethnicity, is the appropriate variable to use when investigating bias. Anaesthesia 2021; 77:354-355. [PMID: 34766336 DOI: 10.1111/anae.15620] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/20/2021] [Indexed: 11/29/2022]
Affiliation(s)
- H L Norton
- University of Cincinnati, Cincinnati, OH, USA
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5
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Jablonski NG. Skin color and race. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2021; 175:437-447. [PMID: 33372701 PMCID: PMC8247429 DOI: 10.1002/ajpa.24200] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 10/23/2020] [Accepted: 11/30/2020] [Indexed: 12/19/2022]
Abstract
Skin color is the primary physical criterion by which people have been classified into groups in the Western scientific tradition. From the earliest classifications of Linnaeus, skin color labels were not neutral descriptors, but connoted meanings that influenced the perceptions of described groups. In this article, the history of the use of skin color is reviewed to show how the imprint of history in connection with a single trait influenced subsequent thinking about human diversity. Skin color was the keystone trait to which other physical, behavioral, and culture characteristics were linked. To most naturalists and philosophers of the European Enlightenment, skin color was influenced by the external environment and expressed an inner state of being. It was both the effect and the cause. Early investigations of skin color and human diversity focused on understanding the central polarity between "white" Europeans and nonwhite others, with most attention devoted to explaining the origin and meaning of the blackness of Africans. Consistently negative associations with black and darkness influenced philosophers David Hume and Immanuel Kant to consider Africans as less than fully human and lacking in personal agency. Hume and Kant's views on skin color, the integrity of separate races, and the lower status of Africans provided support to diverse political, economic, and religious constituencies in Europe and the Americas interested in maintaining the transatlantic slave trade and upholding chattel slavery. The mental constructs and stereotypes of color-based races remained, more strongly in some places than others, after the abolition of the slave trade and of slavery. The concept of color-based hierarchies of people arranged from the superior light-colored people to inferior dark-colored ones hardened during the late seventeenth century and have been reinforced by diverse forces ever since. These ideas manifest themselves as racism, colorism, and in the development of implicit bias. Current knowledge of the evolution of skin color and of the historical development of color-based race concepts should inform all levels of formal and informal education. Awareness of the influence of color memes and race ideation in general on human behavior and the conduct of science is important.
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Affiliation(s)
- Nina G. Jablonski
- Department of AnthropologyThe Pennsylvania State UniversityState CollegePennsylvaniaUSA
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6
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Carratto TMT, Marcorin L, do Valle-Silva G, de Oliveira MLG, Donadi EA, Simões AL, Castelli EC, Mendes-Junior CT. Prediction of eye and hair pigmentation phenotypes using the HIrisPlex system in a Brazilian admixed population sample. Int J Legal Med 2021; 135:1329-1339. [PMID: 33884487 DOI: 10.1007/s00414-021-02554-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 02/26/2021] [Indexed: 01/23/2023]
Abstract
Human pigmentation is a complex trait, probably involving more than 100 genes. Predicting phenotypes using SNPs present in those genes is important for forensic purpose. For this, the HIrisPlex tool was developed for eye and hair color prediction, with both models achieving high accuracy among Europeans. Its evaluation in admixed populations is important, since they present a higher frequency of intermediate phenotypes, and HIrisPlex has demonstrated limitations in such predictions; therefore, the performance of this tool may be impaired in such populations. Here, we evaluate the set of 24 markers from the HIrisPlex system in 328 individuals from Ribeirão Preto (SP) region, predicting eye and hair color and comparing the predictions with their real phenotypes. We used the HaloPlex Target Enrichment System and MiSeq Personal Sequencer platform for massively parallel sequencing. The prediction of eye and hair color was accomplished by the HIrisPlex online tool, using the default prediction settings. Ancestry was estimated using the SNPforID 34-plex to observe if and how an individual's ancestry background would affect predictions in this admixed sample. Our sample presented major European ancestry (70.5%), followed by African (21.1%) and Native American/East Asian (8.4%). HIrisPlex presented an overall sensitivity of 0.691 for hair color prediction, with sensitivities ranging from 0.547 to 0.782. The lowest sensitivity was observed for individuals with black hair, who present a reduced European contribution (48.4%). For eye color prediction, the overall sensitivity was 0.741, with sensitivities higher than 0.85 for blue and brown eyes, although it failed in predicting intermediate eye color. Such struggle in predicting this phenotype category is in accordance with what has been seen in previous studies involving HIrisPlex. Individuals with brown eye color are more admixed, with European ancestry decreasing to 62.6%; notwithstanding that, sensitivity for brown eyes was almost 100%. Overall sensitivity increases to 0.791 when a 0.7 threshold is set, though 12.5% of the individuals become undefined. When combining eye and hair prediction, hit rates between 51.3 and 68.9% were achieved. Despite the difficulties with intermediate phenotypes, we have shown that HIrisPlex results can be very helpful when interpreted with caution.
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Affiliation(s)
- Thássia Mayra Telles Carratto
- Departamento de Química, Laboratório de Pesquisas Forenses e Genômicas, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes, 3900, SP, 14040-901, Ribeirão Preto, Brazil
| | - Letícia Marcorin
- Departamento de Genética, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, 14049-900, Brazil
| | - Guilherme do Valle-Silva
- Departamento de Química, Laboratório de Pesquisas Forenses e Genômicas, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes, 3900, SP, 14040-901, Ribeirão Preto, Brazil
| | | | - Eduardo Antônio Donadi
- Divisão de Imunologia Clínica, Departamento de Clínica Médica, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, 14048-900, Brazil
| | - Aguinaldo Luiz Simões
- Departamento de Genética, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, 14049-900, Brazil
| | - Erick C Castelli
- Departamento de Patologia, Faculdade de Medicina de Botucatu, Unesp - Universidade Estadual Paulista, Botucatu, SP, 18618-970, Brazil
| | - Celso Teixeira Mendes-Junior
- Departamento de Química, Laboratório de Pesquisas Forenses e Genômicas, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes, 3900, SP, 14040-901, Ribeirão Preto, Brazil.
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7
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Palmal S, Adhikari K, Mendoza-Revilla J, Fuentes-Guajardo M, Silva de Cerqueira CC, Bonfante B, Chacón-Duque JC, Sohail A, Hurtado M, Villegas V, Granja V, Jaramillo C, Arias W, Lozano RB, Everardo-Martínez P, Gómez-Valdés J, Villamil-Ramírez H, Hünemeier T, Ramallo V, Parolin ML, Gonzalez-José R, Schüler-Faccini L, Bortolini MC, Acuña-Alonzo V, Canizales-Quinteros S, Gallo C, Poletti G, Bedoya G, Rothhammer F, Balding D, Faux P, Ruiz-Linares A. Prediction of eye, hair and skin colour in Latin Americans. Forensic Sci Int Genet 2021; 53:102517. [PMID: 33865096 DOI: 10.1016/j.fsigen.2021.102517] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 03/19/2021] [Accepted: 03/30/2021] [Indexed: 10/21/2022]
Abstract
Here we evaluate the accuracy of prediction for eye, hair and skin pigmentation in a dataset of > 6500 individuals from Mexico, Colombia, Peru, Chile and Brazil (including genome-wide SNP data and quantitative/categorical pigmentation phenotypes - the CANDELA dataset CAN). We evaluated accuracy in relation to different analytical methods and various phenotypic predictors. As expected from statistical principles, we observe that quantitative traits are more sensitive to changes in the prediction models than categorical traits. We find that Random Forest or Linear Regression are generally the best performing methods. We also compare the prediction accuracy of SNP sets defined in the CAN dataset (including 56, 101 and 120 SNPs for eye, hair and skin colour prediction, respectively) to the well-established HIrisPlex-S SNP set (including 6, 22 and 36 SNPs for eye, hair and skin colour prediction respectively). When training prediction models on the CAN data, we observe remarkably similar performances for HIrisPlex-S and the larger CAN SNP sets for the prediction of hair (categorical) and eye (both categorical and quantitative), while the CAN sets outperform HIrisPlex-S for quantitative, but not for categorical skin pigmentation prediction. The performance of HIrisPlex-S, when models are trained in a world-wide sample (although consisting of 80% Europeans, https://hirisplex.erasmusmc.nl), is lower relative to training in the CAN data (particularly for hair and skin colour). Altogether, our observations are consistent with common variation of eye and hair colour having a relatively simple genetic architecture, which is well captured by HIrisPlex-S, even in admixed Latin Americans (with partial European ancestry). By contrast, since skin pigmentation is a more polygenic trait, accuracy is more sensitive to prediction SNP set size, although here this effect was only apparent for a quantitative measure of skin pigmentation. Our results support the use of HIrisPlex-S in the prediction of categorical pigmentation traits for forensic purposes in Latin America, while illustrating the impact of training datasets on its accuracy.
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Affiliation(s)
- Sagnik Palmal
- UMR 7268 ADES, CNRS, Aix-Marseille Université, EFS, Faculté de Médecine Timone, Marseille 13005, France
| | - Kaustubh Adhikari
- School of Mathematics and Statistics, Faculty of Science, Technology, Engineering and Mathematics, The Open University, Milton Keynes MK7 6AA, UK; Department of Genetics, Evolution and Environment, and UCL Genetics Institute, University College London, London WC1E 6BT, UK
| | - Javier Mendoza-Revilla
- Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima 31, Perú; Unit of Human Evolutionary Genetics, Institut Pasteur, Paris 75015, France
| | - Macarena Fuentes-Guajardo
- Departamento de Tecnología Médica, Facultad de Ciencias de la Salud, Universidad de Tarapacá, Arica 1000000, Chile
| | | | - Betty Bonfante
- UMR 7268 ADES, CNRS, Aix-Marseille Université, EFS, Faculté de Médecine Timone, Marseille 13005, France
| | - Juan Camilo Chacón-Duque
- Division of Vertebrates and Anthropology, Department of Earth Sciences, Natural History Museum, London SW7 5BD, UK
| | - Anood Sohail
- Department of Biotechnology, Kinnaird College for Women, 93 - Jail Road, Lahore 54000, Pakistan
| | - Malena Hurtado
- Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima 31, Perú
| | - Valeria Villegas
- Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima 31, Perú
| | - Vanessa Granja
- Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima 31, Perú
| | - Claudia Jaramillo
- Department of Biotechnology, Kinnaird College for Women, 93 - Jail Road, Lahore 54000, Pakistan; GENMOL (Genética Molecular), Universidad de Antioquia, Medellín 5001000, Colombia
| | - William Arias
- GENMOL (Genética Molecular), Universidad de Antioquia, Medellín 5001000, Colombia
| | - Rodrigo Barquera Lozano
- National Institute of Anthropology and History, Mexico City 6600, Mexico; Department of Archaeogenetics, Max Planck Institute for the Science of Human History (MPI-SHH), Jena 07745, Germany
| | | | - Jorge Gómez-Valdés
- National Institute of Anthropology and History, Mexico City 6600, Mexico
| | - Hugo Villamil-Ramírez
- Unidad de Genomica de Poblaciones Aplicada a la Salud, Facultad de Química, UNAM-Instituto Nacional de Medicina Genómica, Mexico City 4510, Mexico
| | - Tábita Hünemeier
- Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP 05508-090, Brazil
| | - Virginia Ramallo
- Departamento de Genética, Universidade Federal do Rio Grande do Sul, Porto Alegre 90040-060, Brazil; Instituto Patagónico de Ciencias Sociales y Humanas, Centro Nacional Patagónico, CONICET, Puerto Madryn U9129ACD, Argentina
| | - Maria-Laura Parolin
- Instituto de Diversidad y Evolución Austral (IDEAus), Centro Nacional Patagónico, CONICET, Puerto Madryn, Argentina
| | - Rolando Gonzalez-José
- Instituto Patagónico de Ciencias Sociales y Humanas, Centro Nacional Patagónico, CONICET, Puerto Madryn U9129ACD, Argentina
| | - Lavinia Schüler-Faccini
- Departamento de Genética, Universidade Federal do Rio Grande do Sul, Porto Alegre 90040-060, Brazil
| | - Maria-Cátira Bortolini
- Departamento de Genética, Universidade Federal do Rio Grande do Sul, Porto Alegre 90040-060, Brazil
| | | | - Samuel Canizales-Quinteros
- Unidad de Genomica de Poblaciones Aplicada a la Salud, Facultad de Química, UNAM-Instituto Nacional de Medicina Genómica, Mexico City 4510, Mexico
| | - Carla Gallo
- Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima 31, Perú
| | - Giovanni Poletti
- Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima 31, Perú
| | - Gabriel Bedoya
- GENMOL (Genética Molecular), Universidad de Antioquia, Medellín 5001000, Colombia
| | - Francisco Rothhammer
- Instituto de Alta Investigación, Universidad de Tarapacá, Arica 1000000, Chile; Programa de Genetica Humana, ICBM, Facultad de Medicina, Universidad de Chile, Santiago, Arica 1000000, Chile
| | - David Balding
- Department of Genetics, Evolution and Environment, and UCL Genetics Institute, University College London, London WC1E 6BT, UK; Melbourne Integrative Genomics, Schools of BioSciences and Mathematics & Statistics, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Pierre Faux
- UMR 7268 ADES, CNRS, Aix-Marseille Université, EFS, Faculté de Médecine Timone, Marseille 13005, France.
| | - Andrés Ruiz-Linares
- UMR 7268 ADES, CNRS, Aix-Marseille Université, EFS, Faculté de Médecine Timone, Marseille 13005, France; Department of Genetics, Evolution and Environment, and UCL Genetics Institute, University College London, London WC1E 6BT, UK; Ministry of Education Key Laboratory of Contemporary Anthropology and Collaborative Innovation Center of Genetics and Development, School of Life Sciences and Human Phenome Institute, Fudan University, Yangpu District, Shanghai, China.
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Lasisi T. The constraints of racialization: How classification and valuation hinder scientific research on human variation. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2021; 175:376-386. [PMID: 33675042 DOI: 10.1002/ajpa.24264] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 02/15/2021] [Accepted: 02/17/2021] [Indexed: 12/18/2022]
Abstract
Human biological variation has historically been studied through the lens of racialization. Despite a general shift away from the use of overt racial terminologies, the underlying racialized frameworks used to describe and understand human variation still remain. Even in relatively recent anthropological and biomedical work, we can observe clear manifestations of such racial thinking. This paper shows how classification and valuation are two specific processes which facilitate racialization and hinder attempts to move beyond such frameworks. The bias induced by classification distorts descriptions of phenotypic variation in a way that erroneously portrays European populations as more variable than others. Implicit valuation occurs in tandem with classification and produces narratives of superiority/inferiority for certain phenotypic variants without an objective biological basis. The bias of racialization is a persistent impediment stemming from the inheritance of scientific knowledge developed under explicitly racial paradigms. It is also an internalized cognitive distortion cultivated through socialization in a world where racialization is inescapable. Though undeniably challenging, this does not present an insurmountable barrier, and this bias can be mitigated through the critical evaluation of past work, the active inclusion of marginalized perspectives, and the direct confrontation of institutional structures enforcing racialized paradigms.
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Affiliation(s)
- Tina Lasisi
- Department of Anthropology, Pennsylvania State University, State College, Pennsylvania, USA
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Norton HL. The color of normal: How a Eurocentric focus erases pigmentation complexity. Am J Hum Biol 2020; 33:e23554. [PMID: 33337560 DOI: 10.1002/ajhb.23554] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 12/03/2020] [Accepted: 12/06/2020] [Indexed: 11/06/2022] Open
Abstract
OBJECTIVES Skin pigmentation is both a highly variable and highly visible human phenotypic trait. Investigations into the biology and origins of this variation have been the focus of research in the fields of dermatology, anthropology, and forensic science, among others. This manuscript explores how much of what we know about the biology, genetics, and evolutionary origins of pigmentation has been strongly influenced by investigations and applications that focus on lighter skin. METHODS I reviewed literature from the fields of dermatology, anthropology and evolutionary genetics, and forensic science to assess how perceptions of lighter skin as the "normal" state in humans can shape the ways that knowledge is gathered and applied in these fields. RESULTS This normalization of lighter skin has impacted common tools used in dermatology and shaped the framework of dermatological education. A strong Eurocentric bias has shaped our understanding of the genetic architecture of pigmentary traits, which influences the ways in we understand the evolutionary processes leading to modern pigmentation diversity. Finally, I discuss how these biases in pigmentation genetics work in combination with phenotypic systems that privilege predicting lighter pigmentation variation to impede accurate prediction of intermediate phenotypes, particularly in individuals with ancestry from multiple populations. This can lead to a disproportionate targeting of already over-policed populations with darker skin. CONCLUSIONS Potential changes to how we conceptualize clinical and basic pigmentation research may help to reduce existing health disparities and improve understanding of pigmentation genetic architecture and how this knowledge is applied in forensic contexts.
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Affiliation(s)
- Heather L Norton
- Department of Anthropology, University of Cincinnati, Cincinnati, Ohio, USA
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10
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Zheng J, Huo D, Wen H, Shang Q, Sun W, Xu Z. Corneal-Smart Phone: A novel method to intelligently estimate postmortem interval. J Forensic Sci 2020; 66:356-364. [PMID: 33112427 DOI: 10.1111/1556-4029.14611] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 10/07/2020] [Accepted: 10/08/2020] [Indexed: 11/29/2022]
Abstract
The changes of postmortem corneal opacity are often used to roughly estimate the postmortem interval (PMI) in forensic practice. The difficulty associated with this time estimate is the lack of objective means to rapidly quantify postmortem corneal changes in crime scenes. This study constructed a data analysis model of PMI estimation and implemented an intelligent analysis system for examining the sequential changes of postmortem corneal digital images, named Corneal-Smart Phone, which can be used to quickly estimate PMI. The smart phone was used in combination with an attachment device that provided a darkroom environment and a steady light source to capture postmortem corneal images. By segmenting the corneal pupil region images, six color features, Red (R), Green (G), Blue (B), Hue (H), Saturation (S), Brightness (V) and four texture features Contrast (CON), Correlation (COR), Angular Second Moment (ASM), and Homogeneity (HOM), were extracted and correlated with PMI model. The results indicated that CON had the highest correlation with PMI (R2 = 0.983). No intra/intersubject variation in CON values were observed (p > 0.05). With the increase in ambient temperature or the decrease in humidity, the CON values were increased. PMI prediction error was <3 h within 36 h postmortem and extended to about 6-8 h after 36 h postmortem. The correct classification rate of the blind test samples was 82%. Our study provides a method that combines postmortem corneal image acquisition and digital image analysis to enable users to quickly obtain PMI estimation.
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Affiliation(s)
- JiLong Zheng
- Department of Forensic Medicine, Criminal Investigation Police University of China, Shenyang, China
| | - DeMin Huo
- Criminal Investigation Division of Jiading District Bureau of Shanghai Public Security Bureau, Shanghai, China
| | - HongYang Wen
- Center of Software Research and Development, Criminal Investigation Police University of China, Shenyang, China
| | - QingFa Shang
- Department of Forensic Medicine, Criminal Investigation Police University of China, Shenyang, China
| | - WenKai Sun
- Department of Forensic Medicine, Criminal Investigation Police University of China, Shenyang, China
| | - ZiTong Xu
- Department of Forensic Medicine, Criminal Investigation Police University of China, Shenyang, China
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Jonnalagadda M, Faizan MA, Ozarkar S, Ashma R, Kulkarni S, Norton HL, Parra E. A Genome-Wide Association Study of Skin and Iris Pigmentation among Individuals of South Asian Ancestry. Genome Biol Evol 2019; 11:1066-1076. [PMID: 30895295 PMCID: PMC6456006 DOI: 10.1093/gbe/evz057] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/19/2019] [Indexed: 12/14/2022] Open
Abstract
South Asia has a complex history of migrations and is characterized by substantial pigmentary and genetic diversity. For this reason, it is an ideal region to study the genetic architecture of normal pigmentation variation. Here, we present a meta-analysis of two genome-wide association studies (GWASs) of skin pigmentation using skin reflectance (M-index) as a quantitative phenotype. The meta-analysis includes a sample of individuals of South Asian descent living in Canada (N = 348), and a sample of individuals from two caste and four tribal groups from West Maharashtra, India (N = 480). We also present the first GWAS of iris color in South Asian populations. This GWAS was based on quantitative measures of iris color obtained from high-resolution iris pictures. We identified genome-wide significant associations of variants within the well-known gene SLC24A5, including the nonsynonymous rs1426654 polymorphism, with both skin pigmentation and iris color, highlighting the pleiotropic effects of this gene on pigmentation. Variants in the HERC2 gene (e.g., rs12913832) were also associated with iris color and iris heterochromia. Our study emphasizes the usefulness of quantitative methods to study iris color variation. We also identified novel genome-wide significant associations with skin pigmentation and iris color, but we could not replicate these associations due to the lack of independent samples. It will be critical to expand the number of studies in South Asian populations in order to better understand the genetic variation driving the diversity of skin pigmentation and iris color observed in this region.
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Affiliation(s)
- Manjari Jonnalagadda
- Symbiosis School for Liberal Arts, Symbiosis International (Deemed University), Pune, India
| | | | - Shantanu Ozarkar
- Department of Anthropology, Savitribai Phule Pune University, India
| | - Richa Ashma
- Department of Zoology, Savitribai Phule Pune University, India
| | - Shaunak Kulkarni
- Department of Anthropology, Savitribai Phule Pune University, India
| | | | - Esteban Parra
- Department of Anthropology, University of Toronto, Ontario, Canada
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Abstract
Human skin and hair color are visible traits that can vary dramatically within and across ethnic populations. The genetic makeup of these traits-including polymorphisms in the enzymes and signaling proteins involved in melanogenesis, and the vital role of ion transport mechanisms operating during the maturation and distribution of the melanosome-has provided new insights into the regulation of pigmentation. A large number of novel loci involved in the process have been recently discovered through four large-scale genome-wide association studies in Europeans, two large genetic studies of skin color in Africans, one study in Latin Americans, and functional testing in animal models. The responsible polymorphisms within these pigmentation genes appear at different population frequencies, can be used as ancestry-informative markers, and provide insight into the evolutionary selective forces that have acted to create this human diversity.
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Affiliation(s)
- William J Pavan
- Genetic Disease Research Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland 20892, USA;
| | - Richard A Sturm
- Dermatology Research Centre, The University of Queensland Diamantina Institute, The University of Queensland, Brisbane, Queensland 4102, Australia;
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Quillen EE, Norton HL, Parra EJ, Lona-Durazo F, Ang KC, Illiescu FM, Pearson LN, Shriver MD, Lasisi T, Gokcumen O, Starr I, Lin YL, Martin AR, Jablonski NG. Shades of complexity: New perspectives on the evolution and genetic architecture of human skin. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2018; 168 Suppl 67:4-26. [PMID: 30408154 DOI: 10.1002/ajpa.23737] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Revised: 09/17/2018] [Accepted: 09/20/2018] [Indexed: 02/06/2023]
Abstract
Like many highly variable human traits, more than a dozen genes are known to contribute to the full range of skin color. However, the historical bias in favor of genetic studies in European and European-derived populations has blinded us to the magnitude of pigmentation's complexity. As deliberate efforts are being made to better characterize diverse global populations and new sequencing technologies, better measurement tools, functional assessments, predictive modeling, and ancient DNA analyses become more widely accessible, we are beginning to appreciate how limited our understanding of the genetic bases of human skin color have been. Novel variants in genes not previously linked to pigmentation have been identified and evidence is mounting that there are hundreds more variants yet to be found. Even for genes that have been exhaustively characterized in European populations like MC1R, OCA2, and SLC24A5, research in previously understudied groups is leading to a new appreciation of the degree to which genetic diversity, epistatic interactions, pleiotropy, admixture, global and local adaptation, and cultural practices operate in population-specific ways to shape the genetic architecture of skin color. Furthermore, we are coming to terms with how factors like tanning response and barrier function may also have influenced selection on skin throughout human history. By examining how our knowledge of pigmentation genetics has shifted in the last decade, we can better appreciate how far we have come in understanding human diversity and the still long road ahead for understanding many complex human traits.
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Affiliation(s)
- Ellen E Quillen
- Department of Internal Medicine, Section of Molecular Medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina.,Center for Precision Medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina
| | - Heather L Norton
- Department of Anthropology, University of Cincinnati, Cincinnati, Ohio
| | - Esteban J Parra
- Department of Anthropology, University of Toronto - Mississauga, Mississauga, Ontario, Canada
| | - Frida Lona-Durazo
- Department of Anthropology, University of Toronto - Mississauga, Mississauga, Ontario, Canada
| | - Khai C Ang
- Department of Pathology and Jake Gittlen Laboratories for Cancer Research, Penn State College of Medicine, Hershey, Pennsylvania
| | - Florin Mircea Illiescu
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom.,Centro de Estudios Interculturales e Indígenas - CIIR, P. Universidad Católica de Chile, Santiago, Chile
| | - Laurel N Pearson
- Department of Anthropology, Pennsylvania State University, University Park, Pennsylvania
| | - Mark D Shriver
- Department of Anthropology, Pennsylvania State University, University Park, Pennsylvania
| | - Tina Lasisi
- Department of Anthropology, Pennsylvania State University, University Park, Pennsylvania
| | - Omer Gokcumen
- Department of Biological Sciences, State University of New York at Buffalo, Buffalo, New York
| | - Izzy Starr
- Department of Biological Sciences, State University of New York at Buffalo, Buffalo, New York
| | - Yen-Lung Lin
- Department of Biological Sciences, State University of New York at Buffalo, Buffalo, New York
| | - Alicia R Martin
- Analytic and Translational Genetics Unit, Massachusetts General Hospital, Boston, Massachusetts.,Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, Massachusetts.,Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, Massachusetts
| | - Nina G Jablonski
- Department of Anthropology, Pennsylvania State University, University Park, Pennsylvania
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Zheng J, Huo D, Wang J, Zhao K, Teng Y, Ma Y. [Temporal pattern of postmortem color changes in the pupil region of the cornea in rabbits]. NAN FANG YI KE DA XUE XUE BAO = JOURNAL OF SOUTHERN MEDICAL UNIVERSITY 2018; 38:1266-1269. [PMID: 30377122 DOI: 10.3969/j.issn.1673-4254.2018.10.19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
OBJECTIVE To explore the temporal pattern of postmortem color changes in the pupil region of the cornea for noninvasive estimation of the postmortem interval (PMI). METHODS Two rabbit models of air embolism and drowning were established in a dark room at a temperature of 20 ℃ with a relative humidity of 30%. The corneal images of the rabbits were acquired using a digital camera at two-hour intervals within 72 h after death. The pupil region on the corneal images was segmented using computer image processing technique (MATLAB), and the parameters of 6 image color features (RGBHSV) were extracted. Regression analysis was used to analyze the relationship between these parameters and the PMI, and the effects of different death causes on the changes of the corneal color features were also assessed. RESULTS Within 72 h after death from different causes, the R, G and B values of the pupil region on the corneal images all tended to increase with the PMI, showing a good fitting with the PMI (P < 0.01). No significant correlation was found between the values of H, S and V and the PMI (P>0.05). The R, G and B values in the pupil region on the corneal images showed consistent variation trends after death from the two causes, and their correlations with PMI were also similar. The measured values of R, G and B in air embolism group were greater than those in the drowning group. CONCLUSIONS The postmortem color changes of the pupil region on corneal images follow an identifiable temporal pattern and can vary across different causes of death. The regression equations established in this study provide references for non-invasive and objective estimation of the PMI.
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Affiliation(s)
- Jilong Zheng
- Department of Forensic Medicine, Criminal Investigation Police University of China, Shenyang 110035, China
| | - Demin Huo
- Department of Forensic Medicine, Criminal Investigation Police University of China, Shenyang 110035, China
| | - Jiulin Wang
- Criminal Investigation Brigade of Nanchang Public Security Bureau, Nanchang 330000, China
| | - Kaifang Zhao
- Department of Forensic Medicine, Criminal Investigation Police University of China, Shenyang 110035, China
| | - Yue Teng
- Department of Forensic Medicine, Criminal Investigation Police University of China, Shenyang 110035, China
| | - Yu Ma
- Department of Forensic Medicine, Criminal Investigation Police University of China, Shenyang 110035, China
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Rawofi L, Edwards M, Krithika S, Le P, Cha D, Yang Z, Ma Y, Wang J, Su B, Jin L, Norton HL, Parra EJ. Genome-wide association study of pigmentary traits (skin and iris color) in individuals of East Asian ancestry. PeerJ 2017; 5:e3951. [PMID: 29109912 PMCID: PMC5671666 DOI: 10.7717/peerj.3951] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Accepted: 10/01/2017] [Indexed: 01/08/2023] Open
Abstract
Background Currently, there is limited knowledge about the genetics underlying pigmentary traits in East Asian populations. Here, we report the results of the first genome-wide association study of pigmentary traits (skin and iris color) in individuals of East Asian ancestry. Methods We obtained quantitative skin pigmentation measures (M-index) in the inner upper arm of the participants using a portable reflectometer (N = 305). Quantitative measures of iris color (expressed as L*, a* and b* CIELab coordinates) were extracted from high-resolution iris pictures (N = 342). We also measured the color differences between the pupillary and ciliary regions of the iris (e.g., iris heterochromia). DNA samples were genotyped with Illumina’s Infinium Multi-Ethnic Global Array (MEGA) and imputed using the 1000 Genomes Phase 3 samples as reference haplotypes. Results For skin pigmentation, we did not observe any genome-wide significant signal. We followed-up in three independent Chinese samples the lead SNPs of five regions showing multiple common markers (minor allele frequency ≥ 5%) with good imputation scores and suggestive evidence of association (p-values < 10−5). One of these markers, rs2373391, which is located in an intron of the ZNF804B gene on chromosome 7, was replicated in one of the Chinese samples (p = 0.003). For iris color, we observed genome-wide signals in the OCA2 region on chromosome 15. This signal is driven by the non-synonymous rs1800414 variant, which explains 11.9%, 10.4% and 6% of the variation observed in the b*, a* and L* coordinates in our sample, respectively. However, the OCA2 region was not associated with iris heterochromia. Discussion Additional genome-wide association studies in East Asian samples will be necessary to further disentangle the genetic architecture of pigmentary traits in East Asian populations.
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Affiliation(s)
- Lida Rawofi
- Department of Anthropology, University of Toronto at Mississauga, Mississauga, Canada
| | - Melissa Edwards
- Department of Anthropology, University of Toronto at Mississauga, Mississauga, Canada
| | - S Krithika
- Department of Anthropology, University of Toronto at Mississauga, Mississauga, Canada
| | - Phuong Le
- Department of Anthropology, University of Toronto at Mississauga, Mississauga, Canada
| | - David Cha
- Department of Anthropology, University of Toronto at Mississauga, Mississauga, Canada
| | - Zhaohui Yang
- Yunnan Key Laboratory of Primate Biomedical Research, Institute of Primate Translational Medicine, Kunming University of Science and Technology, Kunming, China
| | - Yanyun Ma
- MOE Key Laboratory of Contemporary Anthropology, School of Life Sciences, Fudan University, Shanghai, China
| | - Jiucun Wang
- State Key laboratory of Genetic Engineering, Collaborative Innovation Center for Genetics and Development, School of Life Sciences, Fudan University, Shanghai, China
| | - Bing Su
- State Key Laboratory of Genetic Resources and Evolution, Kumming Institute of Zoology, Chinese Academy of Sciences, Kunming, China
| | - Li Jin
- State Key laboratory of Genetic Engineering, Collaborative Innovation Center for Genetics and Development, School of Life Sciences, Fudan University, Shanghai, China
| | - Heather L Norton
- Department of Anthropology, University of Cincinnati, Cincinnati, United States of America
| | - Esteban J Parra
- Department of Anthropology, University of Toronto at Mississauga, Mississauga, Canada
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Jablonski NG, Chaplin G. The colours of humanity: the evolution of pigmentation in the human lineage. Philos Trans R Soc Lond B Biol Sci 2017; 372:20160349. [PMID: 28533464 PMCID: PMC5444068 DOI: 10.1098/rstb.2016.0349] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/09/2016] [Indexed: 12/16/2022] Open
Abstract
Humans are a colourful species of primate, with human skin, hair and eye coloration having been influenced by a great variety of evolutionary forces throughout prehistory. Functionally naked skin has been the physical interface between the physical environment and the human body for most of the history of the genus Homo, and hence skin coloration has been under intense natural selection. From an original condition of protective, dark, eumelanin-enriched coloration in early tropical-dwelling Homo and Homo sapiens, loss of melanin pigmentation occurred under natural selection as Homo sapiens dispersed into non-tropical latitudes of Africa and Eurasia. Genes responsible for skin, hair and eye coloration appear to have been affected significantly by population bottlenecks in the course of Homo sapiens dispersals. Because specific skin colour phenotypes can be created by different combinations of skin colour-associated genetic markers, loss of genetic variability due to genetic drift appears to have had negligible effects on the highly redundant genetic 'palette' for the skin colour. This does not appear to have been the case for hair and eye coloration, however, and these traits appear to have been more strongly influenced by genetic drift and, possibly, sexual selection.This article is part of the themed issue 'Animal coloration: production, perception, function and application'.
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Affiliation(s)
- Nina G Jablonski
- Department of Anthropology, The Pennsylvania State University, 409 Carpenter Building, University Park, PA 16802, USA
| | - George Chaplin
- Department of Anthropology, The Pennsylvania State University, 409 Carpenter Building, University Park, PA 16802, USA
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Jonnalagadda M, Bharti N, Patil Y, Ozarkar S, K SM, Joshi R, Norton H. Identifying signatures of positive selection in pigmentation genes in two South Asian populations. Am J Hum Biol 2017; 29. [PMID: 28439965 DOI: 10.1002/ajhb.23012] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Revised: 02/14/2017] [Accepted: 04/01/2017] [Indexed: 11/08/2022] Open
Abstract
OBJECTIVES Skin pigmentation is a polygenic trait showing wide phenotypic variations among global populations. While numerous pigmentation genes have been identified to be under positive selection among European and East populations, genes contributing to phenotypic variation in skin pigmentation within and among South Asian populations are still poorly understood. The present study uses data from the Phase 3 of the 1000 genomes project focusing on two South Asian populations-GIH (Gujarati Indian from Houston, Texas) and ITU (Indian Telugu from UK), so as to decode the genetic architecture involved in adaptation to ultraviolet radiation in South Asian populations. METHODS Statistical tests included were (1) tests to identify deviations of the Site Frequency Spectrum (SFS) from neutral expectations (Tajima's D, Fay and Wu's H and Fu and Li's D* and F*), (2) tests focused on the identification of high-frequency haplotypes with extended linkage disequilibrium (iHS and Rsb), and (3) tests based on genetic differentiation between populations (LSBL). RESULTS Twenty-two pigmentation genes fall in the top 1% for at least one statistic in the GIH population, 5 of which (LYST, OCA2, SLC24A5, SLC45A2, and TYR) have been previously associated with normal variation in skin, hair, or eye color. In comparison, 17 genes fall in the top 1% for at least one statistic in the ITU population. Twelve loci which are identified as outliers in the ITU scan were also identified in the GIH population. CONCLUSIONS These results suggest that selection may have affected these loci broadly across the region.
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Affiliation(s)
- Manjari Jonnalagadda
- Symbiosis School for Liberal Arts (SSLA), Symbiosis International University (SIU), Pune, 411014, India
| | - Neeraj Bharti
- HPC-MBA Group, Centre for Development of Advanced Computing, Pune, 411007, India
| | - Yatish Patil
- HPC-MBA Group, Centre for Development of Advanced Computing, Pune, 411007, India
| | - Shantanu Ozarkar
- Department of Anthropology, Savitribai Phule Pune University, Pune, 411007, India
| | - Sunitha Manjari K
- HPC-MBA Group, Centre for Development of Advanced Computing, Pune, 411007, India
| | - Rajendra Joshi
- HPC-MBA Group, Centre for Development of Advanced Computing, Pune, 411007, India
| | - Heather Norton
- Department of Anthropology, University of Cincinnati, Cincinnati, Ohio
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Algee-Hewitt BFB, Goldberg A. Better together: Thinking anthropologically about genetics. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2016; 160:557-60. [DOI: 10.1002/ajpa.23022] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 05/18/2016] [Indexed: 01/22/2023]
Affiliation(s)
| | - Amy Goldberg
- Department of Biology; Stanford University; Stanford California 94305
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