Genes carry the information that determines our traits, which are features or characteristics we inherit from our parents — like eye color, height, and the color and texture of our hair. They also determine things like whether babies will be male or female, the amount of oxygen blood can carry, and the likelihood of getting some diseases. Scientists believe that every human has about 20, to 25, genes. If even one of these genes is missing or has changed mutated , it can cause a disease.
Sometimes a mutation is inherited, just like curly hair or brown eyes. But the technology could also hold great potential as a treatment for human diseases. Here is a list of some of the first diseases that scientists are tackling using CRISPR-Cas technology, testing its possibilities and limits as a medical tool. The gene-editing technology is used to remove the gene that encodes for a protein called PD This protein found on the surface of immune cells is the target of some cancer drugs such as checkpoint inhibitors.
This is because some tumor cells are able to bind to the PD-1 protein to block the immune response against cancer. The trial tested this approach in 12 patients with non-small cell lung cancer at the West China Hospital. The results, published in April , suggested the approach was feasible and safe. Some experts have recommended that the long-term safety of the approach remain under review. Others have suggested using more precise gene-editing approaches such as base editing.
In the US, a phase I trial run by the University of Pennsylvania tested the safety of a similar approach. They then added another gene to help the immune cells recognize tumors. T he results revealed that the treatment was safe in patients with advanced forms of cancer.
The therapy consists of harvesting bone marrow stem cells from the patients and using CRISPR technology in vitro to make them produce fetal hemoglobin. This is a natural form of the oxygen-carrying protein that binds oxygen much better than the conventional adult form. The modified cells are then reinfused into the patient. Hemophilia is another blood disorder that CRISPR technology could tackle, although development is still at the preclinical stage.
Last year, Intellia Therapeutics and Regeneron Pharmaceuticals teamed up to pursue the development of hemophilia treatments based on genome editing. Many hereditary forms of blindness are caused by a specific genetic mutation, making it easy to use CRISPR-Cas9 to treat it by targeting and modifying a single gene. In addition, the activity of the immune system is limited in the eye, which can circumvent any problems related to the body rejecting the treatment.
This is the first time that this gene-editing tool has been tested on clinical-quality human eggs. None of the embryos in this study were implanted or allowed to develop.
According to the Genetic Disease Foundation , there are more than 6, human genetic disorders. To do this, they would need an appropriate piece of RNA to target corresponding stretches of genetic material. The Cas9 enzyme cuts DNA at that spot, which allows scientists to delete, repair, or replace a specific gene.
Diseases caused by a mutation in a single gene include sickle cell disease, cystic fibrosis, and Tay-Sachs disease. These affect millions of people worldwide. These types of diseases, though, are far outnumbered by diseases like cardiovascular disease, diabetes, and cancer, which kill millions of people across the globe each year.
These types of treatments would benefit children and adults who are already living with a genetic disease, as well as people who develop cancer. This approach may also help the 25 million to 30 million Americans who have one of the more than 6, rare diseases. Rare diseases affect fewer than , people in the United States at any given time, which means there is less incentive for pharmaceutical companies to develop treatments.
Last year researchers at the University of California Berkeley made progress in developing an ex vivo therapy — where you take cells out of a person, modify them, and put them back into the body. This treatment was for sickle cell disease.
In this condition, a genetic mutation causes hemoglobin molecules to stick together, which deforms red blood cells. This can lead to blockages in the blood vessels, anemia, pain, and organ failure.
They then injected these cells into mice. The stem cells migrated to the bone marrow and developed into healthy red blood cells.
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