Gene therapy sheep study proves promising enough for human trials

By Maggie Lynch

- Last updated on GMT

(Image: Getty/Bene_A)
(Image: Getty/Bene_A)

Related tags Gene therapy study Animal testing hereditary

A gene therapy trial originally tested in sheep, to treat a condition known as ‘day blindness’, has been approved for in-human trials.

After finding sheep that have a genetic mutation, which caused hereditary achromatopsia​, or day blindness, researchers initiated gene therapy trials that proved to successfully cure the condition.

Day blindness refers to a condition where an individual, human or animal, cannot see in bright light.

Ron Ofri, a researcher on this study from the Hebrew University of Jerusalem, told us that the research team injected the day-blind sheep with adeno-associated virus 2 (AAV2​) that carried a copy of CNGA3. He said that within two weeks the sheep tested regained all vision.

The oldest sheep that was given the treatment is now six years old and still has fully restored vision.

He said, “It’s a [gene] mutation, basically the two main genes that cause day blindness in people are CNGB3 and CNGA3. Our sheep [the sheep from the study] have the mutation CNGA3 which is responsible for about one-third of the cases in people worldwide.”

In-human trial

He further explained, that inherited diseases always have local variations but worldwide about one-third of the people with day-blindness have a mutation on the CNGA3 gene.

Since the gene mutation in sheep is the same gene as a large portion of humans with day-blindness, it was hypothesized that the therapy could work in humans that have the same genetic mutation.

“Because the therapy has proven to be so effective and so safe the US Food and Drug Administration has given approval to begin clinical trials in humans,”​ said Ofri.

In fact, he told us, that clinical trials for this gene therapy are in progress in the US currently.

Israel’s Ministry of Health approved human clinical trials of this therapy in Israel as well, with trials set to begin later this year at the Hadassah Medical Center.

“Basically, it started out just as a case of a weird disease in sheep and nine years later we’re treating people,”​ Ofri added.

The research was completed with Ofri serving as a veterinarian ophthalmologist, another member of the team was an animal geneticist, a retinal surgeon, and a researcher from the University of Florida. 

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