Retinitis pigmentosa (RP) is an inherited disease that results in blindness. Approximately 1 in 4000 individuals have this disease, and it is among the most common inherited retinal disease. In RP patients, the symptoms usually present slowly and long after the disease has progressed. The symptoms of RP do vary person to person but the main symptoms are tunnel vision, night blindness, blurred vision, and then eventually a complete loss of vision.
In this disease, retinal deterioration occurs due to the loss of photoreceptors. Mutations in the rhodopsin and opsin genes have been implicated in RP disease pathophysiology. Rhodopsin is a light-sensitive receptor that has a role in the visual transduction cascade which essentially allows us to see in dim light.
There is no current cure for RP, patients manage their disease with the help of guide dogs and in severe cases, patients may need a bionic eye. The lack of treatment options for RP patients is a big problem but it may change in the future due to the entry of CRISPR.
A study was published in EPFL, whereby scientists used CRISPR-Cas9 gene editing in mice with RP. Scientists wanted to see whether CRISPR editing could prevent retinal deterioration.
The mice had a mutation in the PDE6B gene resulting in RP. The scientists used electroporation to deliver CRISPR and its relevant components into the eyes of the mice. The visual function was assessed in vivo and in vitro using electroretinograms. It was found that retinal functionality and photoreceptor functionality in the CRISPR-edited eyes were preserved. Furthermore, the CRISPR-edited eyes had higher visual acuity compared to the control and this was retained 3 months post-treatment with CRISPR. However, the visual acuity did slightly reduce at P90 but this needs confirmation with long-term experimentation.