It’s not magic – it’s science in progress. Many gene therapies are under investigation and some have been approved for use for conditions other thanA or B. The risks and benefits of each gene therapy are evaluated independently and if a clinical trial for a particular gene therapy is successful, it has the potential to offer a remarkably different approach to the way we’ve historically managed genetic disease. Let’s look at an example:
Gene transfer therapy
Currently undergoing clinical trials in many different conditions, including haemophilia A and B, this method of gene therapy aims to introduce a functioningthat can instruct the body to produce the needed .
CREATING A FUNCTIONAL GENE
The gene transfer process begins when a functional copy of a mutated gene is created in a laboratory. The functional gene is developed to contain the instructions for making a needed protein.
BUILDING A TRANSPORT VEHICLE
DNA is placed in the viral vector
The functional gene now has to be delivered into the body. To protect the gene and allow it to be introduced into the body, a transport vehicle is created from a neutralised virus.
The transport vehicle created from a neutralised virus is called a therapeutic. The neutralised virus is created by removing the inner viral material in a lab, leaving behind an empty protein shell.
Viruses used in gene transfer include, (AAV) and . Ongoing studies are evaluating the body’s immune response to gene therapy.
DELIVERING THE FUNCTIONAL GENE
A functional gene is placed inside the transport vehicle and large numbers are administered via an intravenous infusion. Once the transport vehicle has a functional gene inside, it is called a therapeutic vector. The therapeutic vector is designed to target the functional gene toward a preferred tissue. In haemophilia A and B, the liver is the target because it can make the proteins required for blood to clot. In other diseases, such as, the brain is the target.
When the functional gene is placed inside the AAV, additionalis included that is intended to allow it to work and promote production of the protein only within the targeted . Research is ongoing to understand to what extent the AAV may deliver the functional gene to the body’s other tissues.
Proteins in the body
Once introduced in the body, the new gene is designed to work in place of the gene that isn’t functioning properly. If successful, the goal for this new gene is to provide instructions for the body to make the protein it needs. In the case of haemophilia, the liver is targeted to make the proteins.
The new, functional gene enters theof the targeted cells. There, it is generally expected to reside as an episome, or circular piece of DNA, outside the . The original genetic material found in the chromosomes is intended to be left unchanged. This means the mutated gene would still be there and can be passed on to a person’s offspring. In some cases, the gene integrates directly into the existing DNA. Research is ongoing to better understand the rate and impact of this integration.
Ongoing clinical trials are being conducted to understand how gene therapy will affect the human body. Please be sure to read through the section “WHAT ARE THE RISKS OF GENE THERAPY?”