Genetic diseases in the humans are associated with congenital disorders and phenotypic traits. A single mutation in a gene can cause physical, mental or both problems. Some diseases can be lethal and there is still no cure for them. Over the past few years genomic editing technologies is providing a fast and an effective tool to precisely manipulate the genome at specific locations. Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR/Cas9) is being used for the last few years and has shown advantages in terms of clinical applicability to treat genetic diseases such as Hemophilia, Beta-Thalassemia, Cystic fibrosis, etc.
CRISPR has been a game changer in biomedical research because of the ease and accuracy with which it can be used to edit the genetic code. It is a guide molecule made up of RNA that allows a specific site on the DNA to be targeted. It is normally used along with bacterial enzyme called Cas9 which acts as a molecular scissors, chopping the DNA at exact point required.
HOW DOES CRISPR WORKS?
Scientists start with RNA. That's a molecule that can read the genetic information in DNA. The RNA finds the spot in the nucleus of a cell where some editing activity should take place. This guide RNA shepherd Cas9 to the precise spot on the DNA where a cut is called for. Cas9 then locks onto the double stranded DNA and unzip it. This allows the guide RNA to pair up with some region of the DNA it has targeted. Cas9 snips the DNA at this spot. This creates a break in both strands of the DNA molecule, hence sensing the problem, the cell repairs the break.
Fixing the break might disable the gene. Alternatively, this repair might fix a mistake or even insert a new gene. Cells usually repair a break in their DNA by gluing the loose ends back together. That's a sloppy process. It often results in a mistake that disables some gene. That may not sound useful but sometimes it is.
DISEASES THAT 'CRISPR' TECHNOLOGY COULD CURE
CRISPR Technology could let us edit any mutation at will and cure the disease it causes. In practice, we are just at the beginning of the development of CRISPR as a therapy and there are still many unknowns.
One of the first and most advanced CRISPR clinical trials, which are currently running in China are testing the potential of the gene editing tool in patients with advanced cancer of esophagus. Treatment is carried out at Hangzhou cancer hospital. It starts with the extraction of T cells from the patient. Using CRISPR, the cells are modified to remove the gene that encodes for a receptor called PD-1 that tumors are able to bind to and instruct immune system not to attack. Cells are reinfused into the patient with a capacity to attack tumor cells
First CRISPR trial in Europe will seek to treat beta-thalassemia, a blood disorder that affects the oxygen carrying capacity of blood. The therapy, developed by CRISPR Therapeutics and Vertex Pharmaceuticals, consists in harvesting hematopoietic stem cells from the patient and using CRISPR technology to make them produce fetal hemoglobin, a natural form of the oxygen-carrying protein that binds oxygen much better than the adult form. Hemophilia is another blood disorder that CRISPR technology could tackle.
CRISPR is a great candidate to treat genetic blindness. For many hereditary forms of blindness, the specific mutations causing the disease are known making it easy to instruct CRISPR-Cas9 to target and modify that gene.
There are several ways CRISPR technology could help us in the fight against AIDS. One is using CRISPR to cut the HIV virus out of the DNA of immune cells. This approach could bring the key advantage of being able to attack the latent form of the virus, which is inserted into our DNA and inactive, making it impossible for most therapies to target it.