The stories in your DNA

This exercise is a part of Educator Guide: An Open Book / View Guide

Directions: These questions are based on the article “An open book.” Due to the quantity of content, students should divide into five groups after reading the article, with each group concentrating on one application of genetic testing.  The applications are:

  • Group A: Uncovering interesting trivia about your traits
  • Group B: Identifying mutations associated with serious diseases
  • Group C: Assessing risk of passing along disease-associated mutations to children
  • Group D: Tailoring lifestyle choices
  • Group E: Predicting drug reactions

Each group should answer the following questions, focusing specifically on the assigned application in Questions 5–8. After moving on to Question 9, each group can also share what it has learned with the rest of the class.

1. Name a few companies that offer direct-to-consumer genetic testing. How many people sent DNA samples to such companies in 2017?

Possible student response: Ancestry, 23andMe, Family Tree DNA, Gencove, Genos, Helix, Living DNA, Veritas Genetics, etc. Last year, more than 7 million people sent DNA samples to such companies.

2. Explain the differences between the types of DNA tests described in “How much gets tested?”

Possible student response: Companies sequence different portions of people’s DNA. Some companies, such as Veritas Genetics, do whole genome sequencing. Whole genome sequencing analyzes most of a person’s 6 billion DNA bases. Other companies, such as Genos and Helix, analyze the exome, only the genes that code for proteins. The exome is 60 million to 120 million DNA bases — or about 1 to 2 percent of a person’s DNA. Companies such as 23andMe, Ancestry and others use the SNP chip approach. SNP (pronounced snip) stands for single nucleotide polymorphism. SNPs are variations of single DNA building blocks. 23andMe, Ancestry and other companies only do “spot checks” of SNPs in regions that are associated with certain traits.

3. What are currently available direct-to-consumer genetic tests used for?

Possible student response: At this time, many people use consumer genetic tests for entertainment purposes, such as tracing family trees. Other consumer genetic tests screen for gene variants linked to certain diseases and health conditions, though the tests are limited. Doctors can order reliable genetic tests for certain disease-associated gene variants.

4. How much does whole genome sequencing cost?

Possible student response: Anywhere from less than $1,000 to over $25,000, depending on how extensive the analysis is.

5. What genetic testing application is your group responsible for? In what section(s) of the article did you find relevant information?

Possible student response:

Uncovering interesting trivia about your traits: “Broad business” and “Reality check.”

Identifying mutations associated with serious diseases: “No drama.”

Assessing risk of passing along disease-associated mutations to children: “Carried away.”

Tailoring lifestyle choices: “Reality check.”

Predicting potentially harmful drug reactions: “Drug reactions.”

6. As it relates to your assigned application, what are some things that you could learn from genetic testing?

Possible student response:

Uncovering interesting trivia about your traits: Genetic variations are associated with the photic sneeze reflex, the ability to smell certain scents that roses give off, ear folds, toe length, preference for cilantro and sweet or salty snacks, and detecting asparagus odor in urine. Consumer genetic testing also gives information about physical traits such as hair and eye color, and about ancestry.

Identifying mutations associated with serious diseases: Companies screen for gene variants linked to increased risks for breast cancer, Alzheimer’s disease, Parkinson’s disease, macular degeneration, celiac disease and some other health conditions with well-established genetic connections.

Assessing risk of passing along disease-associated mutations to children: Some gene variants can cause disease if a child inherits copies from both parents. Such diseases are recessive and include cystic fibrosis, phenylketonuria and Tay-Sachs, for example. Other gene variants can cause disease if a child inherits a version from just one parent. Those diseases are dominant and include some types of breast cancer, colon cancer and some cases of high cholesterol, for example.

Tailoring lifestyle choices: Some consumer genetic testing companies claim that DNA analysis can suggest the most effective diet or exercise plan, or otherwise suggest lifestyle choices. However, studies have not supported these ideas.

Predicting potentially harmful drug reactions: Some gene variants can make people either more or less sensitive than average to certain common medications.

7. What data does the article present for your assigned application?

Possible student response: “Traits that tickle” gives some of the genes and numbers of gene variants involved in trivial traits. “The list” shows the chromosomal locations of 59 genes for which variants are known to be associated with serious diseases. “Carried away” discusses the probability of passing on certain disease-associated gene variants to children. The section also discusses the probability that those variants will cause disease in those children. “No help” shows data from a study that found no connection between successful weight loss and participants’ gene variants for fat and carbohydrate metabolism. A study reported in Genome Medicine demonstrates that most people have gene variations that increase or decrease sensitivity to at least one medication.

8. What are some limitations of direct-to-consumer genetic testing?

Possible student response: Though it is possible to determine the risk of developing some diseases, especially if they are linked to single genes, the risks of diseases associated with multiple genes, polygenic diseases, are harder to assess. In 2013, the U.S. Food and Drug Administration prohibited companies from assessing the risk of developing certain polygenic diseases for customers in the United States.

9. After your classmates have shared the information about their applications, summarize the article in two sentences or less?

Possible student response: A number of companies will analyze a person’s DNA for a fee and report back on various interesting traits. There are limitations to the medically relevant information that can be found from such analyses.

10. What questions do you still have after reading the article?

Possible student response: How is the privacy of personal genetic data regulated or guaranteed? How long do the various types of genetic tests take? How much will test prices come down as technology improves and more people use these services? What effect will having personal genetic information have on people’s lives and on society?