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Q&A
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What is genetics?
Genetics is the study of inheritance. Genes are the instruction manuals for making building blocks called proteins, and proteins combine in many ways to create all the parts of our bodies. Proteins also help to create unique body features called traits. Some traits are visible, like eye color. Others are not, like your body's ability to fight certain diseases. Scientists who study genetics are called geneticists.
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Does everybody have the same genes?
Yes and no. While the human genome is mostly the same in all people, slight differences exist. This genetic variation, spread across many genes, makes up much less than 1 percent of each person's genetic material (DNA). Yet the differences are enough to create people with different appearances and different health. These differences are often inherited, so the more closely related two people are, the more similar their DNA is likely to be.
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What does it mean when someone says you have a genetic risk?
It means that you have inherited the tendency to develop a certain illness. Having a genetic risk does not mean that you will develop a particular condition, but rather that you have a higher chance of developing it than if you did not have the risk. Your genes play a role in determining whether or not you will develop certain illnesses. If, for instance, your mother's father had a history of heart disease, you may have inherited that genetic risk from genes you got from your mother (that she got from her father), much as you may also have gotten your grandmother's straight or curly hair. But genes are not the only influence. What you eat, whether and how much you exercise, and other lifestyle factors also affect your health.
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How do scientists find genes linked to human diseases?
Researchers link genes to diseases in two different ways:
Studying a disease. Scientists who are looking for relationships between genes and a disease sometimes start with the disease. For example, since some forms of breast cancer run in families, researchers might suspect that one or more genes plays a part in causing breast cancer in those families. To test that idea, scientists would ask family members to participate in a genetic study so that researchers could search for a genetic variation or combination of variations present only in people who have breast cancer and not in their family members who don't.
Studying genes. Sometimes, research with laboratory animals has yielded a lot of basic information leading scientists to suspect that certain genes and the proteins they produce might be linked to a particular disease. Take heart disease as one example. Researchers have already identified many of the proteins that are important for the proper functioning of the heart. Some of these proteins affect the pumping of the heart, while some others regulate blood pressure or cholesterol levels in the blood. Scientists analyze the genes for those proteins and then conduct studies with DNA from large numbers of people, hoping to find certain patterns of genetic variation that turn up over and over again in people with heart disease. Those variations could turn out to be disease predictors.
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Who pays for research on the role of genes in diseases?
Your tax dollars, through the National Institutes of Health, fund medical research in the United States. The National Institutes of Health provides some of this money to scientists at universities and medical centers to carry out research to identify the roles of genes in various diseases. In the laboratory, geneticists often use organisms that can be bred easily and quickly, like yeast, fruit flies, or mice. The researchers alter the genes in these organisms and watch the outcomes. Because humans have many of the same genes as these experimental organisms, the experiments yield valuable knowledge about human genes and diseases.
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Why do researchers sometimes study ethnic and racial groups?
The genetic material in all humans is 99.9 percent identical. However, since the human genome is made up of 3 billion chemical units strung together, the one-tenth of 1 percent of DNA that is different among people can add up to a few million tiny differences. The average differences between individuals are larger than those between groups. People who belong to groups that share the same ancestry are likely to have genes that are more similar than do people who are not so closely related. Studying the DNA from family members—or from populations in which people share a common ancestry—makes it easier for scientists to pick out the genetic differences linked with disease. Researchers study genes from people in different population groups to find the genetic differences that are unique to certain diseases, not to particular ethnic and racial groups. Occasionally, however, scientists do study members of certain groups because a disease is much more common in that group. The gene linked to Tay-Sachs disease, for example, was identified in Ashkenazi Jews.
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Have researchers figured out how changes in genes can cause disease?
They only know this for some diseases, and genetic variations do not usually cause disease by themselves. So-called complex disorders that affect millions of people—for example, heart disease, depression, and cancer—are affected by variations in many different genes. Many other factors count, too, including diet, exercise, and what we are exposed to in the environment. Researchers have not yet identified most of these disease-causing combinations of genes and other factors. To discover how genetic variation contributes to complex disorders, scientists must keep looking to find the genetic variation that exists among all people.
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What's involved in medical research studies of genetic variation?
Your body is made up ofindividual units called cells, which contain your DNA. If you agree to participate in a genetic study, scientists will collect a small sample of your cells in order to "read" your DNA. One of the simplest ways to do this is to gently rub the inside of your cheek with a cotton swab or collect a sample of blood. Scientists study the DNA from these samples and, through laboratory techniques, they can read the information in your genes.
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How do researchers protect people who volunteer to take part in genetic research?
Participating in any study is voluntary, and there are strong safeguards to protect medical research volunteers. If you decide to participate in a genetic study, the scientists should first explain to you the purpose of the study. You should take time to carefully read the informed consent document, which you are required by law to sign before participating in any research study. This document describes the potential risks and benefits ofthe research and how your privacy will be protected. You may also consider finding out which members of your community were on the Institutional Review Board that by law is required to review and approve all federally funded human research studies.
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Can researchers study my genome without my knowing about it or giving permission?
No. Scientists who conduct research with people are required to follow strict rules that include specifying how DNA samples may be used. In addition to telling you the purpose of the study, the researchers must tell you, before collecting samples of your DNA, whether and for how long your sample will be stored in a facility called a repository.The researchers must also get your permission if your DNA sample will be used by other scientists for future studies. In 2003, the U.S. Government created a safeguard known as the Privacy Rule under the Health Insurance Portability and Accountability Act, or HIPAA. Most hospitals, doctors, and health plans that have your personal health information must follow the Privacy Rule, which helps protect your personal health information from being used or shared without your OK.
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Are there other safeguards for the DNA samples collected by researchers?
Good communication between communities and researchers is a very important aspect of ethically sound genetic research. The National Institute of General Medical Sciences (a part of the National Institutes of Health) provides funding and oversight to its Human Genetic Cell Repository, which houses DNA and cell collections. All the samples in this repository are anonymous, which means that no one can associate you with your sample. Scientists can obtain samples from this repository to use for their genetic research. The National Institute of General Medical Sciences requires that researchers who wish to collect DNA or cell samples from members of communities must first talk to the communities to learn about cultural issues and any other concerns. These discussions educate communities about the risks and benefits of genetic research and enable communities to make informed decisions about participating in a study.
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What are the benefits of genetic research to the groups and populations whose members volunteer to participate?
Studying genes from people who are members of a given group or population can be a good thing for that community as a whole. Research results could ultimately point to treatment or prevention strategies that benefit many people in that community.
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What are the risks of genetic research to the groups and populations whose members volunteer to participate?
Research results could lead to the improper stereotyping of a group or population as being more likely to have a certain disease, even if such associations occur simply because community members were more willing to take part in a study—not because they were more likely to have the disease in the first place. Another potential risk is that individuals could learn something about themselves that they might not want to know.
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