Explainer: What is gene therapy and how can it stop people going blind?

Explainer: A gene is a tiny unit of DNA that helps build our body and tells it how to work.  

It's hereditary - the information inside a gene is passed down to us from our parents.   

Your DNA has around 30,000 genes in it.  

In a genetic disorder, a person's genes are mutated and can't do their jobs properly.   

But now there is gene therapy. Brand new scientific magic.   

It introduces a working version of a mutated gene into the cell where it can do what's it supposed to do. 

Gene therapy has emerged for certain inherited eye conditions like Leber congenital amaurosis or LCA.  

LCA causes severe vision loss due to a mutated RPE65 gene. We've all got this gene.  It is one of the genes that tells your eyes how to properly capture light and vision.  

People with this mutated gene issue may eventually go blind.   

There's a wonder drug, Luxturna, which is basically the working RPE65 gene injected into the back of each eye.  

It can't cure blindness. But it can restore some vision and stop it from getting worse. 

Luxturna is just one kind of gene therapy.  

The scientific magic is here for a bunch of complex conditions like melanoma, spinal muscular atrophy and leukaemia.  

And it's coming for conditions like epilepsy, hearing loss and Alzheimer's. 

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But there's a catch: gene therapy is really expensive.  

Luxturna is one of the top 10 most expensive treatments in the world. It costs a whopping $1.5 million for a one-time shot to both eyes.  

It's been funded in Australia, and the UK, and was even fast-tracked in the USA way back in 2017. But not in New Zealand.  

Luxturna was approved by Medsafe earlier this year, but funding has been stalled by Pharmac who have called for more evidence of its efficacy. 

Now, how many Kiwis need Luxturna?   

We have been told of three people who have this rare genetic condition. Their sight is very limited and is slowly deteriorating day by day. Soon they will be completely blind. 

But the truth is - there could be more people out there. 

Because we don't keep track or test people properly in New Zealand the picture we get of our eye health is blurry.  

One reason is we don't have regular eye testing in our schools. Free eye tests are covered in year 7 but that's only for distance vision.  

We also don't have an official national vision survey. So, there is no formal data on how many people in this country have vision loss and what types of eye conditions they might have.  

Nor is there a government-led eye health strategy to improve our sight as a nation.

Patrick Gower is the host of Paddy Gower Has Issues on Three and ThreeNow.

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