Choroideremia Can Lead to Blindness – But Gene Therapy Might Be Able to Halt It

An article recently published by the Guardian shared the stories of three families affected by recent breakthroughs in gene therapy treatments.

What is Gene Therapy?

Gene therapy is an increasingly common type of treatment for certain genetic conditions. Unlike most other treatments, gene therapy does not rely on a pharmaceutical to achieve its affects – rather, it sort of “tricks” the body into repairing itself using materials provided in the injection.

The injection contains what is essentially a benign virus that has had much of its own DNA stripped away, and replaced instead with a modified “DNA-like material.” Viruses are some of the smallest organisms we know of, and they have a terrific natural ability to slip past our body’s defenses.

When the modified virus is injected into a patient, the rewritten DNA segment inside is released into the body where the targeted cells adopt it as its own. The patient’s improperly-functioning gene is temporarily or completely replaced by the properly-functioning version that was delivered to them through the virus.

Professor Robert MacLaren

Only two decades ago, the now well-established principles behind gene therapy were disregarded as mere science fiction.

One scientist, the United Kingdom’s Professor Robert MacLaren, still remembers when his grant application for a study of gene therapy was denied. The study hoped to discover if gene therapy might be useful for treating certain conditions that cause blindness.

“… It’s a complete waste of time funding such a ridiculously stupid project,” MacLaren remembers his critics saying. It was, perhaps, “the lowest point in his 20-year career.”

That was years ago, though. Today, doctors and scientists widely acknowledge the amazing potential of this radical new treatment. Just last October, Professor MacLaren successfully completed the world’s first gene therapy trial for treating blindness-causing genetic conditions.

MacLaren is understandably proud of the successes both he and the therapy have enjoyed since his grant was rejected all those years ago. “I’d love to go back to them and say: Look what’s going on now.”

Case Studies

Patients from around the world with dozens of different conditions have already enjoyed tremendous results from gene therapy treatments.

Matthew Bishop

Matthew Bishop was 49 when he was in a car accident that he never saw coming. He was driving at low speeds when he turned onto a street into the path of an oncoming car.

Though the collision was minor and neither he nor his partner was seriously injured, Bishop was concerned. Why had he not seen the car that he cut in front of?

A visit to the optometrist revealed that Bishop had very little remaining peripheral vision. He was diagnosed with some form of retinitis pigmentosa, a group of degenerative conditions that affect the retina. Eventually, Bishop was told, he would be totally blind.

Matthew left his job and made preparations for a life without sight. About two years later, Bishop met with Professor MacLaren.

MacLaren narrowed down the diagnosis to the more specific condition called choroideremia, caused by a mutation in Bishop’s CHM gene. MacLaren was encouraged by what he saw – and Bishop was approved for participation in the professor’s groundbreaking clinical trial.

After the operation, which involved surgically detaching Matthew’s retina to inject the modified DNA, Bishop noted amazing improvement in the decline of his vision. In fact, every single patient who successfully received the treatment in the clinical trial experienced improved or maintained vision for up to five years after the procedure.

Almost instantly, the threat of permanent blindness was lifted from Matthew’s life. “That’s pretty life-changing,” Bishop said.

Cameron Harding

Cameron is five years old now, and loves the park, outer space, and his family.

He also has type 1 (severe) spinal muscular atrophy, a disease caused by a mutation in the SM1 gene that causes the premature deterioration of motor neurons – the “triggers” in your nervous system that control the voluntary movement of muscles. When Cameron received his diagnosis, he was only a few weeks old. Not long ago, such a diagnosis could have been a death sentence.

Due to advances in treatment, however, 80% of SMA patients live over two years of age – an improvement of up to 50% from the survival rates of some 40 years ago.

Two weeks after his diagnosis, Cameron received an injection of the drug Spinraza. Spinraza works by attaching a modified strand of DNA to a “backup” gene that produces the same protein as SM1, just in much smaller amounts. This “backup” gene (conveniently called SM2) is thereby adjusted to produce a greater amount of the protein, in order to make up for the malfunctioning SM1 gene.

Since receiving his injection, Cameron has shown signs of improvement. Many children with SMA who receive the treatment go on to regain some level of motor function.

In babies where the condition is detected before symptoms appear, treatment can be even more effective. If caught early enough, these babies learn to walk, talk, and otherwise develop just like any other completely healthy child.

Ayden Anjarwalla

Ayden is just four years old.

Doctors in his family’s native Kenya were unable to diagnose what was wrong when the boy was suddenly unable to stand under his own weight. They encouraged the Anjarwallas to go to the United Kingdom, where Ayden was diagnosed with type 2 spinal muscular atrophy within a week of arriving.

After hearing about the Spinraza, the Anjarwallas started to fight fiercely to get their son into the trial. Getting into a clinical trial can mean dozens of check-ups and tests, and as of January this year, there is still no guarantee that Ayden will be approved to join the study.

The Anjarwallas know that even if Ayden is approved, Spinraza isn’t a miracle cure. It’s difficult to say what his condition could be in a few decades – but the Anjarwalla family hopes that Ayden will, through gene therapy, always retain his abilities to walk, speak, or even breathe.

Gene therapy has had an explosive growth in the past few decades. Do you think progress in the field will slow down or speed up in the coming years? Why or why not? Share your thoughts with Patient Worthy!

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