Can Gene Therapy Cure Vision?

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For those who are affected by blindness linked to genetics or disease, most have simply learned to manage their condition and live happy and productive lives as best they can. While life is certainly easier in the modern world for blind people than it was in ancient times, it has not stopped some researchers from wondering if there were medical treatments that could reverse blindness. The rise of gene-therapy has opened some new possibilities toward restoring sight in people living with rare gene mutations linked to blindness. But does it work?

 

Blindness Explained

There are many things that can cause blindness, including injury, disease or inherited genetic traits. The study which we will discuss today focuses on the third category, and specifically on a gene called RPE65, which produces an essential protein found in the retina and ensures normal eyesight.

The retina consists of cells at the back of the eye which are sensitive to photons of light. Simply put, it’s the part of the eye that receives visual data from the outside world. The RPE65 gene produces the necessary proteins for the retinal cells to function properly. Sometimes however, there can be a mutation in the RPE65 gene which affects its’ ability to produce this protein. Every person inherits two copies of this gene from their parents. If both of the genes have mutations, it can lead to a gradual, progressive blindness which begins during infancy. This usually occurs as a slow decline in peripheral vision, difficultly seeing in dim light, and even eventual loss of central vision. This condition is referred to as “RPE65-mediated inherited retinal dystrophy.”

At the time of this writing, there are no drugs which can treat RPE65-related vision loss, but a new form of gene therapy may hold the answer to restoring sight to people who are affected by this rare condition.

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How the Gene Therapy Works

Gene therapy is a relatively new type of medical treatment which involves introducing foreign genetic material into a cell to compensate for some sort of genetic defect or malfunction in those cells.

Of course, this is a lot easier said than done. You cannot simply slap healthy genes onto unhealthy cells and expect it to work. The genetic material used for treatment must be delivered into the targeted cells in a special way. This is done with a vector, a genetically engineered virus which acts a carrier to transplant the genetic material into the cell. This vector can be introduced via IV, or simply injected directly into the affected area.

In the case of RPE65, it is the faulty genes in the retina which fail to produce the necessary proteins which require treatment. This led a company called Spark Therapeutics to develop an experimental gene therapy called Luxturna. The treatment consists of a series of injections into the eye.

In a study to test the treatment’s effectiveness, 20 patients with RPE65-mediated inherited retinal dystrophy were selected to receive Luxturna. Researchers would then gauge the gene therapy’s effectiveness by the recipient’s ability to navigate a specially built, dimly-lit maze. 18 out of 20 patients who received Luxturna experienced a markedly better ability to navigate the maze versus the control group. A year after the trial, all the control group members received Luxturna as well.

Those are pretty positive results, but if you’re looking for more success stories, look no further than America’s Got Talent teenage contestant Christian Guardino. He received the treatment in an earlier experimental trial when he was a young boy and already losing his sight. The therapy allowed him to regain his sight and continue with his vocal training throughout his childhood. Another successful case was that of Corey Hass, a teenager who is now able to go hunting and fishing with his improved eyesight thanks to gene therapy. Haas was the subject of Dr. Ricki Lewis’ book The Forever Fix: Gene Therapy and the Boy Who Saved It, published in 2012.

 

READ ALSO: 15 Ways You’re Damaging Your Eyesight Without Realizing It Infographic

 

This is very promising news for people living with RPE65-mediated inherited retinal dystrophy, and for anyone living with an inherited genetic disorder. It means that gene therapy really is a viable solution for some conditions. Who knows what kind of progress a few more years of scientific research and development will unlock?

References:

www.cdc.gov

www.ghr.nlm.nih.gov