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Genetics 101
  Genetics and the Future of Medicine

By Amanda Ewart Toland, PhD

Reviewed by Karen Hales, PhD
Last updated January 3, 2011



With the human genome decoded, researchers have the daunting task of sifting through the newly-discovered genes in search of those that lead to disease. These efforts will change the way we view diseases and receive medical care.

 
 
 

What Are Genetic Researchers Really Trying to Figure out?

The Human Genome Project recently announced that they had sequenced all of the human chromosomes — about three billion bases long. In itself, this is a huge achievement, but knowing the sequence doesn't tell researchers what the 30,000 to 50,000 genes actually do in the body. Their next step is to figure out what the genes do, and what role these genes may play in disease.
Once researchers know which genes are involved in a disease, they can develop a test to screen people who are at risk and also start looking for a cure.

Once researchers know which genes are involved in a disease, they can develop a test to screen people who are at risk and also start looking for a cure. A diagnostic test by itself will not cure the disease, but it can help identify high-risk people who may require more intensive screening or preventative action. Knowing what genes cause a given disease can also help researchers understand what goes wrong in that disease, which can help drive the search for drugs that counteract the problem.

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All Discoveries Are not of Equal Importance

When newspapers announce that a gene has been discovered for a certain disease, it can really mean a number of things.

  • Finding the gene: Sometimes, researchers have identified a gene that definitely causes a disease, such as the discovery of the gene for hemophilia or cystic fibrosis. Such a finding does not necessarily mean that researchers can cure the disease, or that a genetic test is immediately available, but it does mean that the medical community may be closer to an possible cure.
  • Finding one of many genes: Other times, researchers have discovered a gene that plays a role in a small subset of people who get a common disease, such as the genes BRCA1 and BRCA2, which are the cause for some people's breast cancer. Again, finding these genes puts researchers one step closer to a cure or genetic test that can help some people with the disease.
  • Finding a gene in animals: One way to understand gene function in in humans is to find and manipulate a gene that causes an animal — such as the mouse or fruit fly — to show symptoms similar to a human disease. Animals have genes that are very similar to our own, so these discoveries help point researchers to the biological function of a human disease gene. However, it is a long path from finding a gene in flies or mice to finding a genetic treatment for the human disease.

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The Impact on Diagnostics

There will be more genetic tests available to help doctors diagnose the cause of a disease.
As researchers discover the role genes play in disease, there will be more genetic tests available to help doctors make diagnoses and pinpoint the cause of the disease. For example, heart disease can be caused either by a mutation in certain genes, or by environmental factors such as diet or exercise. Doctors can easily diagnose a person with heart disease once they have symptoms. However, doctors can't easily tell what the cause for the heart disease is in each person. Thus, all people receive the same treatment regardless of underlying cause of the disease. In the future, a panel of genetic tests for heart disease might reveal the specific genetic factors that are involved in a given person. People with a specific mutation may be able to receive treatment that is targeted to that mutation, thereby treating the cause of the disease rather than just the symptoms. Also, people with genetic risk may be able to receive preventitive treatment before symptoms become apparent.

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The Impact on Risk Assessment

Currently, doctors take a brief family medical history for their patients. This helps primary care physicians tell if there are genetic factors that may influence a patient's health. But a family history does not provide a doctor with the compete picture of a person's risk. Some people may be at risk for an early-onset disease, even if they do not have a family history of that disease. Similarly, not every person with a strong family history of a disease will inherit the risk factors.

Individual risk assessments will be created for each patient based on that patient's set of genes
Doctors are just beginning to be able to screen people for genetic risk factors present in their family. Some of these predictive tests include testing for predisposition to certain types of hereditary colon and breast cancer. In the future, it may be possible for doctors to screen their patients for many genetic-based risks — those that run in their family and those that don't — all at the same time. Individual risk assessments will be created for each patient based on that patient's set of genes.

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The Impact on Prevention and Treatment Strategies

Knowing their personal risk makes it possible for individuals to decrease their chance developing the disease
By knowing which genes are involved in disease, researchers can develop better medical treatments and prevention strategies that are specific for those gene defects. Knowing their personal risk makes it possible for individuals to decrease their chance developing the disease through lifestyle changes, more aggressive disease surveillance, and preventative medical treatments. In certain instances, we already have more personalized medicine because of advances in genetics; in the future these medical benefits will only expand.
Personalized Medicine

Different people metabolize drugs differently. For example, drugs quickly leave the bloodstream in some people, and linger for a long time in other people. Many of these differences are due to genetic variation. Drugs in the future may not only be better targeted to the cause of the disease, there may also be better choices for people who react to drugs in specific ways.


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