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The Evolving Genetics of Disease Resistance



Author:

Jennifer M. Dechaine
Department of Biological Sciences / Department of Science Education
Central Washington University
dechaine@cwu.edu

Abstract:

This interrupted case study for the flipped classroom applies evolutionary genetics research to human health. Students learn about a naturally occurring, but rare, allele of the CCR5 gene, CCR5-Δ32, which provides resistance to HIV. They use data from primary literature sources to predict and interpret worldwide patterns of CCR5-Δ32 frequency distribution. They then discuss how these allele frequency patterns may have been driven by selection imposed by various diseases or by other evolutionary mechanisms. Next, they test published data using Hardy-Weinberg equilibrium to examine if CCR5-Δ32 also provides genetic resistance to West Nile virus. Finally, they complete a jigsaw discussion of Nature News articles that report on how CCR5 research is being used to develop therapies to treat HIV. Originally written for the evolution portion of a yearlong biology series for undergraduate majors, the case is also appropriate for some non-majors biology courses or, with added complexity, upper-level evolution, genetics, or cell biology courses.

Objectives:
  • Apply real genetics and evolution research to human health.
  • Describe how HIV enters immune cells and how CCR5-Δ32 impedes this process.
  • Predict how selection, driven by disease, will change allele frequencies for one gene (CCR5), and compare these predictions to published results.
  • Test for Hardy-Weinberg equilibrium and interpret test results as they apply to genetic disease susceptibility.
  • Discuss how CCR5 research is being used to develop therapies to treat HIV.
  • Write research questions.
  • Use prior knowledge to predict results.
  • Draw conclusions from quantitative data in figures and tables.
Keywords: Hardy-Weinberg equilibrium; HWE; selection; CCR5; HIV; resistance; selection; CRISPR
Topical Area: N/A
Educational Level: Undergraduate lower division
Formats: PDF
Type/Method: Flipped, Interrupted, Jig-Saw, Journal Article
Language: English
Subject Headings: Biology (General)   Cell Biology   Genetics / Heredity   Medicine (General)   Biotechnology   Evolutionary Biology   Public Health   Molecular Biology   Science (General)   Mathematics  
Date Posted: 1/25/2018
Date Modified: N/A
Copyright: Copyright held by the National Center for Case Study Teaching in Science, University at Buffalo, State University of New York. Please see our usage guidelines, which outline our policy concerning permissible reproduction of this work.

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Videos

The following video(s) are recommended for use in association with this case study.

  How the World Joined Together to End AIDS for Children
This video shows how far the world has come in preventing AIDS in children worldwide. Running time: 5:42 min. Produced by UNICEF, 2016.

  Faces of HIV Trailer
This trailer summarizes the personal stories of diverse Floridians living with HIV. Running time: 2:07 min. Produced by the Florida Department of Health, 2011.

  HIV and CCR5
This is a whiteboard-style video that introduces students to the basics of HIV and AIDS, the mechanism that HIV uses to enter a CD4 immune cell, how CCR5-Δ32 inhibits this mechanism, and CCR5 genetics. Running time: 6:14 min. Created by Jennifer M. Dechaine for the National Center for Case Study Teaching in Science, 2017.




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