At what point in evolutionary development does a group of individuals become two distinct species? This case addresses that fundamental question by asking students to decide whether apple maggot flies are distinct as a species from hawthorn maggot flies. In making their decision, students examine the different models of speciation and consider the primary forces that effect evolutionary change. Developed for an advanced undergraduate course in evolutionary biology, it would be appropriate for any biology course in which students are taught about the models of speciation. It could also be used in a general ecology course in which students consider the distribution and use of resources leading to niche specialization or in a genetics course if restrictions in gene flow are taught in the context of speciation.

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.

This case study takes a combined directed and discussion approach to explore risk factors for breast cancer. After a preparatory reading assignment, students assess various medical histories derived from actual women with breast cancer and rank their overall risk for breast cancer and make recommendations for risk reduction. The task is complicated by the different and often combined sources of risk (e.g., reproductive history, hormone replacement therapy and family history). Originally written for an introductory biology course, the case study could easily be adapted for upper division curses in genetics, physiology, or biochemistry to explore the biological and biochemical basis underlying various risk factors.

This dilemma case, designed for use in an undergraduate genetics course, explores the basic genetic concepts underlying the cloning process as well as the ethical, medical, political, economic, and religious issues surrounding human cloning. While the case presents a fictitious scenario, it is based on the story of Charleston attorney and former state delegate Mark Hunt and his wife Tracey, who privately funded human cloning after the death of their infant son Andrew.

In this "clicker case," students are introduced to Abby, a college student who has been diagnosed with ovarian cancer. As they follow Abby's plight, students learn about basic cellular and genetic mechanisms that are responsible for cancer formation, gaining a general understanding of how cells become cancerous through genetic mutations, how cancers can spread throughout the body by metastasizing, and how modern medicine is currently treating patients diagnosed with cancer through surgery, radiation, and chemotherapy. Developed for use in a large introductory biology course, the case consists of a PowerPoint (~2MB) presented in class that is punctuated by multiple-choice questions the students answer using "clickers." The case can be adapted for use without these technologies.

Since caffeine is a widely used substance, especially by college age students, this case on the effects of caffeine on the human body serves as a real-world connection to many students' lives. The case is divided into sections covering background information on caffeine, cell biology and signal transduction, Parkinson's disease, cardiovascular effects, and addiction/withdrawal. The case was designed so that a section can be used alone or in combination with other sections, as dictated by topic/curriculum needs. It would be appropriate for use in a variety of science and health related courses, including anatomy and physiology, disease related courses, genetics, cell biology, molecular biology, biochemistry, and neuroscience.

In this discussion case, parents must decide whether or not to enroll their sons in an experimental treatment program designed to alleviate the symptoms of muscular dystrophy. The case explores the genetics and physiology of the disease as well as the issues involved with pharmaceutical research. The case has been used in both majors' and non-majors' biology courses, where it is introduced during a unit on the cardiovascular and muscular systems.

This interrupted case study follows the declining health of an infant who suffers from recurrent infections and finally is diagnosed with severe combined immunodeficiency (SCID). The case was developed for use in an undergraduate upper-level immunology course to supplement discussion of B and T cell development and the generation of antibody diversity. It could also be modified for use in a genetics class, with emphasis on the molecular aspects of RAG-mediated recombination and inheritance patterns of the disease, or a pathophysiology class, with emphasis on the physiology underlying the symptoms.

This case is based on Kate Chopin's short story "Desiree's Baby," a tragic tale of race and gender in antebellum Louisiana first published in 1893. Students read the story and then answer a series of questions about the genetics and evolution of skin color. The case was developed for a general biology course organized around the general theme of evolution. It could also be used in anthropology and biology courses for non-majors.

In this case, developed for an introductory genetics class, students meet a woman whose family has a history of colon cancer. Students create a pedigree based on information from the case and discuss what it means to be genetically predisposed to cancer. Using bioinformatics tools from the NCBI database, students identify and examine the mutation in the woman's APC gene that results in genetic predisposition to colon cancer. Finally, they investigate the biological function of the APC protein to understand why this mutation contributes to the development of cancer and determine whether APC is a proto-oncogene, tumor suppressor gene, or genome stability gene.

This directed case study on a genetic disorder was developed for an exam on genetics for a general biology course. The case is based on an article by scientist and author Jared Diamond titled "Founding Fathers and Mothers" that appeared in Natural History magazine in June 1988. In the article, Diamond illustrates the significance of the "founder effect" in small isolated populations like the one described in this case.

This case is based on a research paper about the lignin content of genetically modified corn published in the American Journal of Botany. Students are asked to analyze and discuss the paper, focusing on questions related to experimental design and interpretation and a critique of the statistical data presented. Developed for use in an upper-level undergraduate course in plant ecology and a graduate biostatistics course, the case could also be used in courses in plant anatomy, plant physiology, soil ecology, agriculture, or genetics.

In this dilemma case, the central character, Kathy, must decide whether or not to be tested for known mutations in the breast cancer genes. Students assume the roles of members of Kathy's book club and, using a jigsaw technique, explore the advantages and disadvantages of genetic testing. This case is appropriate for courses that deal with genetics, bioinformatics, biology of cancer, disease prevention, or ethical decision-making.

Most students have heard about situations in which the paternity of a child is questioned, but maternity? This case was designed for introductory biology students and asks them to develop hypotheses to explain how a mother cannot be genetically related to two of her three sons. Through an interrupted, progressive disclosure format, students reject hypotheses and form new ones as data is revealed. This case involves concepts in genetics, inheritance, and the formation of pedigrees. At the conclusion, students are asked to think about the moral, ethical, and legal implications of the mother's rare condition.

This case study was developed to complement the study of the immune system and to emphasize the crosstalk that occurs at the cellular level between B and T cells for proper immune system function. In reading the story of a young couple trying to understand the cause of their infant boy's constant bacterial infections, students review the different classes of antibodies, their specific functions, and how they arise through isotope switching. In addition, students apply their knowledge of basic genetics as they examine how X-linked disorders are passed along and the role of genetic counselors in medicine.

In this interrupted case study, Greg and Olga, a young couple planning a family, have decided to see a genetic counselor because of a family history of genetic disease. Students construct a pedigree from the information presented in the case; then, on the basis of that, determine if the couple are carriers for any recessive genetic diseases and the likelihood of their passing those diseases on to their children. Students learn about the inheritance of single gene dominant, recessive, and sex-linked disorders as well as the significance of carrier frequency. Originally developed for use in a non-science major general biology course, the case has also been used in a human genetics course for non-science majors.

In this interdisciplinary case, students meet Josie, the main character, who suffers from a variety of symptoms. Students must grapple with the conflicting data presented, which ultimately leads them to a diagnosis of either porphyria or schizophrenia. This case can be used in many ways depending on the focus of the course and the instructor. In its simplest form, it can be used to develop content-specific knowledge on the genetic illness porphyria and/or the psychological illness schizophrenia. In an interdisciplinary context, it can be used as a way to discuss complex modes of inheritance and types of confounding issues a genetic counselor, social worker, psychiatrist, or psychologist might face when trying to sort through a complex family history to develop a pedigree or genogram. The case has been used successfully with majors and non-majors in psychology, biology, and genetics. Optional extensions to the case provide for reflection on the theme of "science in society" and how the perception of disease has changed over time.

This case uses the real story of Dawn Langley Simmons, who may have been misidentified as male at birth, to illustrate the developmental basis of human sexual dimorphism and how gender misidentification may occur. Students also consider the emotional, legal, and societal implications of gender misassignment and reassignment. Designed for a junior-level human genetics course for allied health students, the case could be used in a number of other courses including physiology, endocrinology, developmental biology, general biology, and psychology.

When a 30-year-old genetic counselor learns that her 38-year-old sister has developed early onset familial Alzheimer's disease (EOFAD), a dominantly inherited disorder that led to their father's death at age 42, she struggles with whether to undergo genetic testing and whether to have children. This interrupted case study examines the impact of genetic testing on people and their families when there is no treatment or cure for a disease. It covers principles of Mendelian inheritance as well as genetic and reproductive technologies ,such as gene tests, pre-implantation genetic diagnosis, and in vitro fertilization. It can be used in introductory biology courses for both majors and non-majors or adapted for more advanced courses in genetics and molecular biology.