The Basics

Pharmacogenetics examines the relationship between an individual’s genetic makeup and his or her response to a particular drug. The hope is to tailor drugs to an individual or group of individuals who are genetically similar. The goal is to increase a drug’s effectiveness while decreasing its side effects. One piece of information that can be obtained is an individual’s haplotype. A haplotype is “a combination of alleles that are located closely together on the same chromosome and that tend to be inherited together.”1 Due to single-nucleotide polymorphisms (substitution changes), or SNPs, individuals may vary in these alleles and thus vary in their haplotypes. In other words, the combination of the different SNPs in a particular region of your DNA on a single chromosome is your haplotype for that region. Groups of individuals may share the same polymorphisms (or haplotypes) and therefore may respond better as a group to a particular treatment or medication. A different group may have a different set of polymorphisms, and thus haplotypes, and may respond better to a different treatment or medication. Therefore, drug companies may test a medication on different haplotype groups to determine its effectiveness and efficacy for specific groups of people.

The Lesson

Complete the following to gain a deeper understanding of pharmacogenetics

• Go to http://learn.genetics.utah.edu/content/pharma/snips/ to read about SNPs and haplotypes.
• Explore a leukemia example by completing the activity here: Your Doctor's New Genetic Tools
• Complete the Pus-Poppin Frogs activity on the school computers to experience these ideas from the drug company's perspective.
• Read this page http://www.cancer.gov/cancertopics/factsheet/risk/brca to learn about genetic testing for BRCA1 and BRCA2, the statistics associated with these mutations, and the choices one must make as a result of the test findings.

Ethical Issues

• Cancer Free at 33 and Weighing a Mastectomy - read this article about a 33 year old woman with a BRCA1 mutation deciding to have a preventive mastectomy. Also be sure to look at the graphic 'Living with the BRCA Gene: One Family's Story', which is a family tree with commentary by each member located on the left side of the first page of the article. Answer the following questions in your notebook.
  • What were the important issues for Deborah Lindner?
  • Was the information presented well by the author?
  • Would you change the way the author presented the data regarding risk and the interpretation of the genetic test?
• Angelina Jolie - Here is Angelina Jolie's op-ed regarding her preventive mastectomy choice in case you are interested in reading that.
• What Angelina Jolie Forgot to Mention - read this brief article to maintain an overall perspective on the risk of breast cancer and BRCA mutations.