Vision loss is a common disease in our population and it would benefit many people if researchers could find a potential cure. It is believed that 4% of people who are blind are effected by a disease called choroideremia. Choroideremia
is mostly found in males and is caused by a defective CHM gene failing to produce the protein,
REP-1. This disease affects around 1 in every 50,000 males and can be seen early on when male adolescents begin to lose their night vision.
The
REP-1 protein specifies in maintaining healthy retina cells; without this protein
the cells in the eye will stop working and eventually die off. Researchers are
proposing a gene therapy to prevent the death of the eye cells by inserting an
adeno-associated virus vector which will infect the cells of the eye and will target
the DNA, replacing the missing REP-1 protein. The injection of this harmless
virus will be administrated to males at a young age to potentially prevent any future
blindness. This procedure would be similar to that of cataract surgery as it
would take about 40 minutes and the surgeon would detach the patient’s retinas
and insert the injection. This injection in theory would genetically cure
choroideremia.
This injection has been performed on a wide selection of patients. It has been
experimented on males from a range of perfect vision to almost a complete loss
of vision and from the ages of 35 to 63. Every patient experienced some degree
of success in improving their vision (the amount of vision gained depended on
their original vision).
This
gene therapy is a necessary scientific breakthrough as it is prudent that
people are able to see in order to function in everyday life. With the
advancement of curing blindness through gene therapy, the medical field would
be able to improve many people’s lives.
Gene Therapy may Help Against Rare Blindness
Disease. (2017). WebMD. Retrieved from:
http://www.webmd.com/eye-health/news/20140116/gene-therapy-may-restore-sight-in-people-with-rare-blinding-disease#2
Knapton,
Sarah. (2014). Gene therapy heralds cure for blindness. The Telegraph. Retrieved
from: http://www.telegraph.co.uk/news/science/science-news/10574603/Gene-therapy-heralds-cure-for-blindness.html
Xue, K., Groppe, M., Salvetti, P.A. &
MacLaren, E. R. (2017). Technique of
retinal gene
therapy: delivery of viral vector into the subretinal space. Nature.com,
31, 1308-1316. doi: 10.1038/eye.2017.158
After reading this post, the inheritance pattern must be X linked as this genetic disease mostly affect the males like color blindness. In fact, based on Genetics Home Reference, choroideremia is an X-linked recessive disorder; thus, males who are affected have only one altered copy of X chromosome. Since the disease is affected by a defect in a single gene, I would presume CRISPR/Cas9 technique could be another option to treat the genetic defect. The article by Peng et al. stated that CRISPR/Cas9 have been used in conjunction with adeno-associated virus vector to successfully treat choroideremia in mice. The CRIPR/Cas9 is also important in targeting (precision) and repairing mutated gene. I have now learned not only males are prone to color blindness, but night blindness as well. This was a very interesting post.
ReplyDeleteChoroideremia. (2017). Genetics Home Reference. Retrieved from https://ghr.nlm.nih.gov/condition/choroideremia#inheritance
Peng, Y., Tang, L., Yoshida, S., & Zhou, Y. (2017). Applications of CRISPR/Cas9 in retinal degenerative diseases. International Journal of Ophthalmology. 10(4): 646-651. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5406646/