In our last blog article, we discussed how bioinformatics uses techniques to write your personal “genome book,” which contains your entire genetic sequence, then edits your book to find mistakes or differences in your genome (approximately three million). These errors, or mutations, can have different consequences. Some mutations have no effect. These changes we can ignore and focus on the more interesting “mistakes.” Other mutations can either switch a gene off completely or on too high (overexpression). When this happens, the cells in your body get the wrong instructions.
Turning a gene off can mean that an essential protein in your body is not made. If a gene is turned on too high, or overexpressed, it may cause too much of a certain protein to be made, and that’s a bad situation for the cells of your body. Mutations that alter gene expression can cause disease. Scientists continue to identify which mutations are responsible for causing certain diseases to connect the dots between mutation and disease. With a growing body of research literature, we can use this information to connect an individual’s “genome book” with the cause of disease. This is also how we can begin to “personalize” the medical treatment.
Of course this makes personalized medicine sound much simpler than it actually is. One challenge is the massive amount of data, millions of mutations, and knowing which errors to focus on. This requires us as researchers to use heavy computer power and statistical models to identify patterns and figure out the cause of disease. Most diseases are caused by more than one gene, and it is difficult to interpret the downstream effects of every mutation. We also don’t know which genes many drugs target, and most drugs target more than one gene. In short, we don’t know what all of the errors mean!
Researchers and physicians share several success stories despite the challenges of personalized medicine, especially in treating cancer. Let us tell you about three exciting examples:
- Example #1: Nic Volker was a child who was failing to thrive because of a severe intestinal inflammation condition known as inflammatory bowel disease. Researchers sequenced his genome in order to diagnose the cause of his mysterious symptoms and found a single mutation, or error, in his XIAP gene. A mutation in this gene causes a blood disorder that can be treated with a bone marrow transplant, and with this treatment Nic is now healthy! Read the full story.
- Example #2: By sequencing, researchers found that approximately 50 percent of melanomas have a mutation in the gene for BRAF that makes the gene turn on at all times, instead of acting like an on/off switch. They are now using drugs that target BRAF and inhibit it from staying “on.” Read the full story.
- Example #3: Breast cancer tumors are tested for the overexpression of the HER2/neu receptor. Patients with elevated expression of HER2/neu are treated with an antibody drug that targets the HER2/neu receptor. By doing so, the drug specifically turns this gene off.
These are just three examples of how the wealth of information in personal “genome books,” or genome sequences, can be applied to medicine. By working together, bioinformatics researchers and physicians can use the sequence information to treat disease in new ways. With each new discovery, the list grows!
Dr. Julie Dragon and Dr. Marni Slavik are researchers in Microbiology and Molecular Genetics at the University of Vermont. Dr. Dragon is also the Director of the Molecular Bioinformatics Shared Resource (MBSR) for the Larner College of Medicine at UVM (http://www.uvm.edu/medicine/mbsr/ ).