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Bloodline: A Human Genetics Case


Peggy Brickman
Department of Plant Biology
University of Georgia


In this "clicker" case, based on a TV drama about a family secret that only knowledge of genetics can solve, students apply what they have read and heard about genetic diseases to determine familial relationships and predict the chance that a family member has inherited a genetic condition. The case is designed for use in a one-semester introductory biology course taken primarily by freshmen and sophomores to fulfill a general education requirement, but it could be used in any introductory biology course to help students understand and practice applying concepts related to human genetics. In addition, the case could be expanded or modified for use in a genetics or anatomy and physiology class in which human genetics and pedigrees are taught. The case is presented in class using a PowerPoint presentation (~1MB) punctuated by questions that students respond using "clickers" before moving on to the next slide. It could be adapted for use without these technologies.

  • Given parental genotypes, identify the possible gametes and make Punnett squares to determine the genotypic and phenotypic ratios of predicted offspring.
  • Construct pedigrees and be able to distinguish patterns of inheritance seen in pedigrees such as the differences between autosomal and sex-linked and recessive and dominant patterns of inheritance.
  • Use pedigree analysis to develop a hypothesis for how a certain disease in transmitted.
  • Weigh evidence such as a pedigree chart or incomplete transmission to determine the probability that an individual will develop a certain disease.
Keywords: Human genetics; pedigree analysis; autosomal recessive; x-linked recessive; autosomal dominant; blood clotting
Topical Area: N/A
Educational Level: Undergraduate lower division, Undergraduate upper division
Formats: PDF, PowerPoint
Type/Method: Clicker, Interrupted
Language: English
Subject Headings: Genetics / Heredity   Biology (General)   Medicine (General)  
Date Posted: 3/3/2011
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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I have searched for case study information of this nature for some time and all I can say is thank you. This will be the type of challenge needed in my class. Great ideas and information.

Jackie Rogers
Aberdeen High School
Aberdeen MS 39759
I am using this case for a Genetics course, and there is an additional application one could consider incorporating at the end for further discussion: To tie together the hemophilia and factor V leiden components, consider the current research to analyze how factor V leiden may compensate for some cases of hemophilia - maybe explaining why the factor V leiden mutation is as prevalent in the population as it is. This opens up additional discussion for how phenotype can be influenced by multiple genes.

Beth Jones-Mason
University of South Florida
Tampa, FL

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