A news story that garnered a lot of attention on our social media channels recently was the first reported correction of a genetic retinal disease gene in stem cells by the CRISPR/Cas9 gene-editing system. But what is gene editing and what does it mean for people living with genetic retinal conditions?
CRISPR/Cas9 was developed only three years ago as a technique, but has quickly been heralded as a major breakthrough in genetic engineering. This technology allows for the quick, easy and precise editing of DNA. Whereas traditional gene therapy is used to add “corrected” versions of genes, gene editing sets about fixing the underlying defect within the gene. Traditional gene therapy has proven challenging to deliver genes such as the ABCA4 gene associated with Stargardt disease to the retina because of their large size. Gene editing offers a huge potential for conditions which are limited by current technologies.
However, this technique has not yet been tested as a therapy in humans and many questions remain unanswered about the safety of this approach. The study reported on our social media corrected a defect in the RPGR gene associated with X-linked retinitis pigmentosa (RP) and was performed by University of Iowa and Columbia University scientists on stem cells derived from a patient with RP who donated a skin sample for the research. The scientists managed to correct the RPGR mutation in approximately 13% of the patient stem cells. Although promising, there is still much work to be done to advance this approach and to ensure that the researchers are not creating any other alterations to the rest of the individual’s genome which could be detrimental.
Gene editing is truly a revolutionary step forward for all genetic disease, not just retinal conditions and offers tremendous potential. With this potential also come legitimate concerns, such as safety of the approach and the ability of the technique to permanently alter the sperm and egg cells. A huge challenge facing the scientific and patient community over the coming years will be to come together in order to decide what should and what should not be altered by such a powerful tool.
The article referred to above is: Precision Medicine: Genetic Repair of Retinitis Pigmentosa in Patient-Derived Stem Cells. Alexander G. Bassuk, Andrew Zheng, Yao Li, Stephen H. Tsang & Vinit B. Mahajan. Scientific Reports 6, Article number: 19969 (2016) doi:10.1038/srep19969.