CHOOSING TARGETS FOR GENE THERAPY
Gene therapy could potentially treat certain disorders at the source by repairing the underlying genetic flaws. Many disorders or medical conditions might be treated using gene therapy, but others may not be suitable for this approach.
How do you know whether a disorder is a good candidate for gene therapy?
For any candidate disorder, you need to answer the following questions:
- Does the condition result from mutations in one or more genes? For you to even consider gene therapy, the answer must be "yes."
- Which genes are involved? If you plan to treat a genetic flaw, you need to know which gene(s) to pursue. You must also have a DNA copy of that gene available in your laboratory. The best candidates for gene therapy are the so-called "single-gene" disorders - which are caused by mutations in only one gene.
- What do you know about the biology of the disorder? To design the best
possible approach, you need to learn all you can about how the gene factors into the disorder.
- Which tissues are affected?
- What role does the protein encoded by the gene play within the cells of that tissue?
- Exactly how do mutations in the gene affect the protein's function?
- Will adding a normal copy of the gene fix the problem in the affected tissue? This may seem like an obvious question, but it's not. What if the mutated gene encodes a protein that prevents the normal protein from doing its job? Mutated genes that function this way are called dominant negative and adding back the normal protein won't fix the problem. Learn more about how researchers are trying to address dominant negative mutated genes in New Approaches to Gene Therapy.
- Can you deliver the gene to cells of the affected tissue? The answer will come
from several pieces of information, including:
- How accessible is the tissue? Is it fairly easy (skin, blood or lungs), or more difficult to reach (internal organs)?
- What is your best mode of delivery? You can examine the pros and cons of potential delivery methods in Tools of the Trade.
If you can answer "yes" to Questions 4 and 5, then the disorder may be a good candidate for a gene therapy approach.
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