2018 SACNAS Graduate Student Oral Presentation Award

Melissa Spear
University of California, San Francisco
San Francisco, CA


The Role of Recent Demography in Shaping Patterns of Genetic Variation in US Hispanic/Latino Populations

Melissa Spear, Biomedical Sciences Graduate Program, Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, Dara Torgerson, , Department of Pediatrics, University of California, San Francisco and Ryan Hernandez, , Department of Bioengineering and Therapeutic Sciences, Institute for Human Genetics, Institute for Computational Health Sciences, Quantitative Biosciences Institute, University of California, San Francisco

The evolutionary forces of natural selection and demography, including migration, have shaped patterns of worldwide genetic variation, which in turn have shaped the genetic architecture of human phenotypic variation. In the United States, population demography has changed over the 20th century as a result of immigration and this will continue to be one of the primary modes of population growth as the US approaches a “minority-majority” country. Hispanics/Latinos, the largest and fastest growing group, are a genetically heterogeneous population as result of admixture between African, European, and Native American populations. The effect of these large-scale migrations in contributing to shaping genetic variation and subsequently phenotypic variation is unknown. For 9,646 Hispanics/Latinos from the Hispanic Community Health Study/Study of Latinos (HCHS/SOL) we tested the hypothesis that the admixture process in the US has been dynamic over the 20th century. Using RFMix we estimated global and local ancestry and investigated how ancestry has changed over time as a function of birth year. We then used TRACTS to compare the observed lengths of ancestry tracts to different demographic models of migration scenarios with individuals grouped by decades. Our results have shown an increase in Native American ancestry in Mexican Americans over time due to longer tracts of Native American ancestry. Our results suggest that the admixture process in the US has been dynamic in the last century, thus demonstrating a crucial need to improve our understanding of the role of demographic history in shaping the genetic architecture of phenotypic variation in Hispanic/Latino populations.

San Antonio, October 11-13, 2018


  1. Spear, ML, Diaz-Papkovich, A, Ziv, E, Yracheta, JM, Gravel, S, Torgerson, DG, Hernandez, RD. Recent shifts in the genomic ancestry of Mexican Americans may alter the genetic architecture of biomedical traits. Elife 2020; 9 : . PubMed PMID:33372659 PubMed Central PMC7771964.
  2. Spear, ML, Hu, D, Pino-Yanes, M, Huntsman, S, Eng, C, Levin, AM, Ortega, VE, White, MJ, McGarry, ME, Thakur, N et al.. A genome-wide association and admixture mapping study of bronchodilator drug response in African Americans with asthma. Pharmacogenomics J 2019; 19 (3): 249-259. PubMed PMID:30206298 PubMed Central PMC6414286.
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  4. Brehm, JM, Ramratnam, SK, Tse, SM, Croteau-Chonka, DC, Pino-Yanes, M, Rosas-Salazar, C, Litonjua, AA, Raby, BA, Boutaoui, N, Han, YY et al.. Stress and Bronchodilator Response in Children with Asthma. Am J Respir Crit Care Med 2015; 192 (1): 47-56. PubMed PMID:25918834 PubMed Central PMC4511425.
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Dana Crawford

Professor of Population and Quantitative Health Sciences and Associate Director of the Cleveland Institute for Computational Biology, with interest in pharmacogenomics, electronic health records, and diverse populations. Also, an avid foodie!

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